Correct Answer: A

Rationale: The correct answer is A: 'Undesirable.' In this context, 'adverse' means harmful or undesirable, specifically referring to the negative side effects experienced from the medication. Choice B, 'Frequent,' is incorrect as 'adverse' does not imply how often the side effects occur but rather their nature. Choice C, 'Noticeable,' is incorrect as 'adverse' does not necessarily mean that the side effects are easily noticeable, but rather that they are harmful. Choice D, 'Constant,' is incorrect as 'adverse' does not indicate that the side effects are continuous but rather that they are negative.

Correct Answer: C

Rationale: The term 'flexible' accurately describes the type of tube used in the given context. A 'solid' tube would not have been suitable for navigating a curved pipe as it is not pliable. 'Rigid' implies stiffness and inflexibility, making it unsuitable for the task. 'Perforated' means pierced with holes, which is unrelated to the plumber's task of opening up a curved pipe.

Correct Answer: A

Rationale: The correct answer is A: 'Plethora.' In the context provided, 'cornucopia' is used metaphorically to signify an abundance or a large variety of stimulating questions and conversation. 'Plethora' is a synonym for 'cornucopia' and means an excessive amount or abundance. Choices B, C, and D are incorrect. 'Ostracism' means exclusion or rejection, 'Laborious' means requiring a lot of effort, and 'Pensive' means engaged in deep thought.

Correct Answer: B

Rationale: The correct answer is 'Stimuli.' When forming the plural of 'stimulus,' the correct form is 'stimuli.' Choice A, 'Stimulus,' is the singular form, not the plural. Choice C, 'Stimulis,' is an incorrect spelling. Choice D, 'Stimula,' is also an incorrect form for the plural of 'stimulus.' Therefore, 'Stimuli' is the only correct plural form.

Correct Answer: B

Rationale: The correct answer is 'B: Toddler.' A toddler is a young child typically between the ages of one and three who is just learning to walk. 'Obese' (choice A) refers to excess body fat, 'Geriatric' (choice C) pertains to elderly individuals, and 'Hale' (choice D) means strong and healthy, none of which are descriptive of a small child learning to walk.