Which fetal development occurs during the second trimester? Bones begin to harden. The roof of the mouth forms. The eyes can sense changes in light. The heart and circulatory system begin to develop.​

The correct answer is - The roof of the mouth forms.

Explanation:

In humans, 9 months of pregnancy can be divided into three trimesters which means approximately 12 weeks per trimester. Each trimester has specific fetal development.

The second trimester that starts after 12 weeks to 24 or 25th week of pregnancy and known for forming the joint bones, opening the eyes, movements of the fetus, and development of the palate or cleft which means the roof of the mouth develop in this time period of pregnancy.