Carbon and hydrogen have similar electronegativities and combine together to form hydrocarbon molecules. what type of bonds form between these atoms?

The type of bond formed between carbon and hydrogen is NON POLAR COVALENT BOND.
Covalent bond involves sharing of atoms between two elements; each element will donate electrons which will be equally shared by the elements involved. In the case of carbon and hydrogen, carbon has four electrons in its outermost shell, therefore it will form a covalent bond with four atoms of hydrogen each of which will donate one electron.

Ithink due to shortage of water

A- a reduction in biodiversity