Fraternal twins are produced when

Some important events in the human female reproductive cycle are given below. Arrange the events in a proper sequence. $A \rightarrow$ secretion of $FSH$,$B \rightarrow$ growth of corpus luteum,$C \rightarrow$ growth of the follicle and oogenesis,$D \rightarrow$ ovulation,$E \rightarrow$ sudden increase in the level of $LH$.

What is the oestrous cycle?

$A$ single ejaculation contains $...A...$ to $...B...$ million spermatozoa. Semen has a pH of $...C...$ to $...D...$. Its alkalinity helps to neutralize the acidity of the urethra. Here $A, B, C$ and $D$ refer to:

$I.$ Sperm cells,when released from the body and placed in a petri plate,remain alive for a much longer duration.
$II.$ Semen contains chemicals that cause the female's smooth muscles to contract.

Ovulation can be detected by