Final answer:
Option B, which states, "In particular, how do young children, who are constantly encountering new situations, decide how hard to try?", best restates the answer to Part A.
Step-by-step explanation:
The selection from the passage that best restates the answer to Part A is Option B, which states, "In particular, how do young children, who are constantly encountering new situations, decide how hard to try?" This restatement captures the essence of the question being asked and provides a clear explanation of what the passage is trying to explore.