Final answer:
During the first trimester of pregnancy, the major developmental task for the mother is accepting the pregnancy, which is crucial for her emotional well-being and the healthy development of the fetus.
Step-by-step explanation:
The major developmental task that the mother must accomplish during the first trimester of pregnancy is A) Acceptance of the pregnancy. During this critical time, the foundation of the body's basic structures is laid down, including the development of the limb buds, heart, and eyes. The mother's physiological and psychological adaptation to pregnancy begins, which includes accepting and internalizing the fact that she is carrying a new life. This acceptance is important for establishing a healthy prenatal environment and for the mother's emotional well-being.