What happens during the first trimester?

The correct answer is option D, that is, the major organ systems have started developing.

Explanation:

The first trimester lasts until the thirteenth week of pregnancy. During this time the body goes through extreme modifications as it is accommodating a developing baby. In the initial few weeks after conception, the levels of hormone change substantially.  

The first trimester plays an essential part in the growth of the baby. The baby develops all its vital organs by the termination of the third month, thus, it is an important time.  

answer: 21

step-by-step explanation:

divide 630 by 30. 30 goes into 630 21 times

cellular respiration oxidizes food into energy in the form of atps.

glycolysis (6 c hexose) > 2x atps are used > 6c hexose biphosphate > 2 x 3c triphosphate >

2 x 3c pyruvate (2x nadh produced from nad) and (4x atp produced)

pyruvate actively pumped mitochondrial matrix.