Correct Answer: B

Rationale: The correct answer is B: Regression. Regression is a common defense mechanism where a child reverts to an earlier stage of development, such as thumb-sucking, to cope with stress. In this scenario, the 6-year-old boy is using thumb-sucking (a behavior typical of earlier developmental stages) as a way to deal with the stress of surgery. Repression (choice A) involves unconsciously blocking out thoughts or feelings, which is not applicable in this case. Rationalization (choice C) is a defense mechanism where illogical or unreasonable explanations are provided to justify behavior, which is not relevant here. Fantasy (choice D) refers to the use of imagination to escape from reality, which is also not the appropriate defense mechanism for the situation described.

Correct Answer: C

Rationale: Fear of strangers typically begins around 6 months as infants start recognizing familiar and unfamiliar faces, which is part of their social development.

Correct Answer: A

Rationale: Baby powder can be inhaled by the infant and cause respiratory distress. Toys should be inspected to prevent choking hazards. Allowing an infant to take a bottle to bed can increase the risk of aspiration, and hard foods like teething biscuits should be given with caution.

Correct Answer: B

Rationale: At 10 months, children are beginning to understand simple commands like "no." It is important for parents to reinforce this understanding consistently to help the child learn about boundaries and safety.

Correct Answer: A

Rationale: To calculate the dosage, multiply the child's weight (10 kg) by the dosage (8 mg/kg) which equals 80 mg. Since the concentration is 100 mg/5 mL, to find out how much to administer, you need to determine how many 5 mL doses are in 80 mg. It will be 80 mg · 100 mg * 5 mL = 4 mL. Therefore, the correct answer is 4 mL. Choice B, 2 mL, is incorrect because it does not account for the correct dosage calculation. Choice C, 5 mL, is incorrect as it does not consider the dosage based on the child's weight. Choice D, 3 mL, is incorrect as it does not reflect the accurate dosage calculation.