In the cells of the human body, oxygen molecules are used directly in a process that (1) releases energy (2) digests fats (3) synthesizes carbohydrate molecules (4) alters the genetic traits of the cell

The answer is (1)

In the cell of the body, oxygen is used in a process that releases energy. Oxygen is used in the last and most important step in cellular respiration namely the electron transport chain.

In this process electrons are passed from one electron carrier to another and as they are  thus transferred, energy is released. Toward the final step, electrons are transferred  to oxygen which is the final acceptor of the electrons. By the time the process ends, 34 ATP molecules are produced.

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.