In which of the following ways is the general development of a fetus different during the first and third trimesters? a. the skeleton develops fully during the first trimester, and muscles and skin develop during the third. b. skin, muscles, and skeleton form during the first trimester and internal organs develop during the third. c. body parts are created during the first trimester, and they complete their development during the third. d. the blastocyst creates a large ball of cells during the first trimester and it forms into body parts during the third.

The correct answer is C. Body parts are created during the first trimester, and they complete their development during the third.

The first 12 weeks of pregnancy is the first trimester. This trimester is also regarded as the embryonic stage because developing baby is called embryo. During this trimester, body parts such as eyes, ears, the nasal passage, arms, legs, hair follicles, mouth are formed. The sex organs are developed by the end of this trimester.

The third and final trimester starts 25 weeks after pregnancy. All the body parts of the baby formation completed. The movement of the fetus in the womb increases.