Correct Answer: A

Rationale: The correct answer is A. The initial event in a primary immune response is the phagocytosis of pathogens by macrophages and the subsequent presentation of their antigens, which is crucial for initiating the adaptive immune response. Neutrophils (Choice B) are also involved in the innate immune response, but they typically respond after macrophages. B lymphocytes (Choice C) produce antibodies later in the adaptive immune response, and Helper T cells (Choice D) help in coordinating the immune response but are not the first cells to act in a primary immune response.

Correct Answer: C

Rationale: Nociceptors are specialized sensory receptors that detect and transmit signals related to pain. These receptors are activated by noxious stimuli that can potentially cause tissue damage or injury, triggering the perception of pain in the brain. Therefore, the correct answer is 'Pain.' Choices A, B, and D are incorrect because nociceptors specifically respond to painful stimuli, not deep pressure, vibration, or temperature.

Correct Answer: A

Rationale: The correct answer is A: 'Contractile, excitable, elastic, extensible.' All types of muscle tissue share these four properties. Muscle tissue can contract, respond to stimuli, stretch and return to its original shape (elastic), and extend or stretch (extensible). Choice B is incorrect because not all muscle tissues are voluntary (some are involuntary). Choice C is incorrect because not all muscle tissues are voluntary. Choice D is incorrect because not all muscle tissues are voluntary and lack the elastic property.

Correct Answer: A

Rationale: The measurements are close to the true value of 9.8 m/s^2 and are also close to each other, indicating both accuracy and precision. Accuracy refers to how close a measurement is to the true value, while precision refers to how close repeated measurements are to each other. In this case, the measurements are accurate because they are close to the accepted value of 9.8 m/s^2, and they are precise because they are clustered closely around each other. Therefore, choice A, 'They're both accurate and precise,' is the correct answer. Choice B is incorrect because the measurements are precise as they are close to each other, but they are also accurate as they are close to the true value. Choice C is incorrect because the measurements are accurate as they are close to the true value, and choice D is incorrect because the measurements exhibit both accuracy and precision in this scenario.

Correct Answer: D

Rationale: Synergists play multiple roles in muscle function. They assist primary movers in completing specific movements by working together with them. Additionally, synergists help stabilize the point of origin and provide extra pull near the insertion, contributing to the efficiency of movement. Furthermore, they also help prevent unwanted movement at a joint by ensuring that the intended motion is executed smoothly. Therefore, all the statements in the answer choices accurately describe the functions of synergists, making 'All of the above' the most comprehensive and precise description of their role.