Interactions between cells always involve a structure known as a

Interactions between cells always involve a structure known as a connexins.

Explanation:

Connexins is composed of specific type of protein called transmembrane proteins. This structure is responsible for the interaction between the cells. Cells communicate with each other by secreting specific chemicals in which information is present. These chemicals consist of neurotransmitter and harmones.

desert perennials often survive by remaining dormant during dry periods of the year, then springing to life when water becomes available. most annual desert plants germinate only after heavy seasonal rain, then complete their reproductive cycle very quickly.

c.           is the correct answer