By the time they reach adulthood, most people can perform many different activities involving motor skills. Motor skills involve such diverse tasks as riding a bicycle, threading a needle, and cooking a dinner. What all these activities have in common is their dependence on precision and timing of muscular movement.This paragraph best supports the statement that

By the time they reach adulthood, most people can perform many different activities involving motor skills. Motor skills involve such diverse tasks as riding a bicycle, threading a needle, and cooking a dinner. What all these activities have in common is their dependence on precision and timing of muscular movement.
This paragraph best supports the statement that

most adults have not refined their motor skills.

all adults know how to ride a bicycle.

refined motor skills are specifically limited to adults.

threading a needle is a precise motor skill.

Explanation:

Answer: Option d
The second sentence states that threading a needle involves motor skill. The other choices are not in the paragraph.