What is the main cause of variations among organisms during sexual reproduction?

Which among the following statements are true for unisexual flowers?
$(i)$ They possess both stamen and pistil
$(ii)$ They possess either stamen or pistil
$(iii)$ They exhibit cross pollination
$(iv)$ Unisexual flowers possessing only stamens cannot produce fruits

In the given figure,the parts $A, B$,and $C$ are sequentially:

Write true or false for the statement: The development of the child inside the mother's body takes approximately eleven months.

In the process of grafting,what is the part of the plant that possesses the root system called?

In which plant does vegetative propagation occur through leaves?