Which statement describes the first trimester?

• A. Major organs & nervous system develops
• B. Fetus begins movement
• C. The placenta is delivered
• D. Heart forms

Answer: (A)

In the first trimester, the main concept is that the embryo is laying down the foundations for the body’s major organs and the nervous system. Weeks 1–12 are a period of rapid development called organogenesis, when the brain, spinal cord, heart, gut, lungs, and other organ systems begin to form and specialize. The nervous system especially starts early, with the neural tube forming and closing in the first month, setting the stage for brain and spinal cord development.

Movement isn’t felt by the mother until much later in pregnancy, often around mid-pregnancy, so that’s not a hallmark of the first trimester. The placenta forms early to support the growing embryo, but it isn’t delivered until birth. While the heart does begin to develop and beat during the first trimester, the broader statement about major organs and the nervous system better captures what’s happening across the whole body during this stage.