What is the oestrous cycle?

Adolescence is a bridge linking .......... and .......... .
$(i)$ Adolescence $(ii)$ Childhood $(iii)$ Old age $(iv)$ Adulthood

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Endometrium is necessary for implantation of blastocyst.
Reason $R$: In the absence of fertilization,the corpus luteum degenerates that causes disintegration of endometrium.
In the light of the above statements,choose the correct answer from the options given below:

An egg with yolk in the center and cytoplasm surrounding it is known as:

The figure shows a section of human ovary. Select the option which gives the correct identification of either $A$ or $B$ with function/characteristic.

Choose the correct option regarding the statements provided:
$(1)$ The process of fusion of a sperm with an ovum is called fertilization.
$(2)$ $LH$ surge induces the rupture of the Graafian follicle.
$(3)$ An $8$-celled embryo is called a morula.
$(4)$ The length of the fallopian tube is $8-10 \, cm$.