B) One swims freely and the other often lives attached to a hard surface.
Answer:
A. The heartbeat can be heard
Explanation:
After the first trimester, during the fourth month, the heartbeat of the fetus becomes loud enough to be heard with the help of a stethoscope placed on the abdomen of the mother.
From fifth to the seventh month of the development, kicks and jabs are felt by the mother as the fetal legs grow and develops. Languo, a wrinkled pink colored skin covers the fetus.
Languo is in turn covered with a white greasy substance called vernix caseosa.
From eighth to ninth months, rotation of the fetus places its head pointing towards the cervix to facilitate childbirth later.
The development of testes takes place in the seventh month while the body hairs become disappeared in the eighth month.
