Questions: Which of the following statements regarding physical growth is most likely to be true of John and Judy, both six years old? John is likely to be much taller than Judy, hitting a prepubescent growth spurt earlier than Judy. Both John and Judy's brains are fully developed. John and Judy are done losing their primary teeth. John and Judy have likely begun to lose their primary teeth.

The answer is the last one: John and Judy have likely begun to lose their primary teeth.

Explanation for each option:

1. John is likely to be much taller than Judy, hitting a prepubescent growth spurt earlier than Judy.

   • This statement is unlikely to be true for six-year-olds. At this age, significant height differences due to prepubescent growth spurts are not common, as these typically occur later, closer to adolescence.

2. Both John and Judy's brains are fully developed.

   • This statement is incorrect. At six years old, children's brains are still developing. Brain development continues into adolescence and even early adulthood.

3. John and Judy are done losing their primary teeth.

   • This statement is incorrect. Most children begin to lose their primary teeth around the age of six, but they are not done losing them at this age.

4. John and Judy have likely begun to lose their primary teeth.

   • This statement is correct. It is common for children around the age of six to start losing their primary teeth as their permanent teeth begin to emerge.

In summary, the most likely true statement regarding physical growth for six-year-olds John and Judy is that they have likely begun to lose their primary teeth.