Correct Answer: A

Rationale: The correct answer is A: 'foodborne illnesses.' The passage discusses how foodborne illnesses are contracted by consuming contaminated food or beverages, the symptoms they can cause, common sources of contamination like bacteria, viruses, and chemicals, and preventive measures. While the passage mentions dangers associated with uncooked food, bacteria, and proper food preparation, the primary focus is on foodborne illnesses caused by various contaminants. Choice B, 'the dangers of uncooked food,' is incorrect as it is a narrower focus compared to the broader topic of foodborne illnesses. Choice C, 'bacteria,' is incorrect as it is one of the contaminants discussed in relation to foodborne illnesses but not the central subject of the passage. Choice D, 'proper food preparation,' is incorrect as it is mentioned in the passage but not as the main subject; rather, it is discussed as a preventive measure to avoid foodborne illnesses.

Correct Answer: C

Rationale: The author's primary purpose in writing the essay is to inform the reader about how an electrocardiograph reads the electric currents emitted by the heart. Choice A is incorrect because there is no attempt to persuade the reader to have an ECG. Choice B is incorrect because the essay is focused on providing information rather than entertaining with a heartwarming story. Choice D is incorrect as the essay does not primarily analyze the difference between the SA node and the AV node; instead, it focuses on explaining how an electrocardiograph reads electric currents from the heart.

Correct Answer: C

Rationale: In the context of the second paragraph, 'phenomenon' refers to something significant and unusual, specifically describing the scientific phenomenon known as the Doppler Effect. This effect explains the change in frequency of sound waves when a source of sound and the observer are in relative motion. Choices A, B, and D are incorrect because they do not accurately reflect the meaning of 'phenomenon' in this context. 'Lifeless to the senses,' 'nonchalant,' and 'chemical in origin' do not align with the description of the Doppler Effect, which is a notable and uncommon scientific occurrence.

Correct Answer: A

Rationale: The correct answer is A. Baroreceptors and chemoreceptors send impulses from the arteries, while the kidneys control blood volume. Baroreceptors and chemoreceptors are responsible for monitoring blood pressure by sensing changes in pressure, oxygen levels, carbon dioxide levels, and pH within the arteries. They send out impulses to raise or lower blood pressure accordingly. On the other hand, the kidneys play a crucial role in regulating blood volume by absorbing salts and water and removing waste products. This key difference highlights that while baroreceptors and chemoreceptors are involved in monitoring and regulating blood pressure, the kidneys primarily focus on controlling blood volume. Choice B is incorrect because it inaccurately states that baroreceptors and chemoreceptors help maintain blood volume, which is not their primary function. Choice C is incorrect as it provides an inaccurate comparison between the roles of baroreceptors, chemoreceptors, and the kidneys. Choice D is incorrect as it wrongly associates the location of baroreceptors and chemoreceptors with the adrenal cortex, which is not accurate.

Correct Answer: C

Rationale: In the context provided, 'pathogens' refers to disease-causing substances such as bacteria and viruses. These microorganisms can contaminate food and lead to foodborne illnesses. Choice A ('diseases') is incorrect as pathogens themselves cause diseases but are not diseases. Choice B ('vaccines') is incorrect as vaccines are used to prevent diseases caused by pathogens. Choice D ('foods') is incorrect as pathogens are not foods, but rather contaminants that can be found in food.