What is the process called in which waste by-product are removed from the body and discarded outside ?

Excretion

The correct answer is Option (3) – Excretion

When chemical reactions use the carbon source and the oxygen for energy generation, they create by-products that are not only useless for the cells of the body, but could even be harmful.

These waste byproducts are therefore needed to be removed from the body and discarded outside by a process called excretion .