Which one of the following does not occur in a cockroach leg?

The basic unit in the eye of a cockroach/insect is:

Which of the following statement$(s)$ is/are correct regarding cockroaches?
$(i)$ The body of the cockroach is segmented and divisible into three distinct regions - head,thorax and abdomen.
$(ii)$ Blood vascular system is of closed type.
$(iii)$ They are monoecious and both sexes have well developed reproductive organs.
$(iv)$ The development of $P. americana$ is paurometabolous,meaning there is development through nymphal stage.

The dorsal sclerite (tergum) is joined to the ventral sclerite (sternum) on the sides by:

The cockroach is .........

Describe the structure of oothecae in cockroach.