In the fourth week after conception, a miniscule blood vessel that will become the _____ begins to pulsate.
A) lungs
B) stomach
C) kidneys
D) heart

Question

Quizplus · Accepted Answer

In the fourth week after conception, the heart begins to form and a minuscule blood vessel, known as the fetal heart tube or primitive heart tube, begins to pulsate. This marks the beginning of the development of the circulatory system. The lungs, stomach, and kidneys also begin to form around this time but do not start functioning until later in fetal development.

In the Fourth Week After Conception, a Miniscule Blood Vessel