Final answer:
The first trimester is the most important time of pregnancy because it is when the baby's organs begin to form, and the placenta is formed to provide nutrients and remove waste.
Step-by-step explanation:
The most important time of pregnancy is the first trimester because that is when the baby's organs begin to form. During this time, the placenta is formed, which takes over the nutrient and waste requirements of the embryo and fetus. This organ passes nutrients from the mother's blood to the placenta and removes waste from it. In addition, the first trimester is when the basic structures of the body, such as the limb buds, heart, eyes, and liver, are laid down.