Which of the following cannot pass through the placenta into the foetus?

Identify the figure shown below.

After one month of pregnancy,the embryo's $A$ is formed. By the end of the $B$ month of pregnancy,the foetus develops limbs and digits. By the end of $C$,most of the major organ systems are formed,for example,the limbs and external genital organs are well-developed. By the end of $D$,the body is covered with fine hair,eyelids separate,and eyelashes are formed. Here $A$ and $D$ refer to:

Given below is a graph with respect to levels of hormones in a pregnant female. Select the correct option.

The allantois has the similar layers as present in the yolk sac. These are

The function of the allantois in mammals is: