Question

how the Sun is responsible for most of the energy on Earth by explaining it's connection to photosynthesis and fossil fuels.

Answer 1

The sun provides most of the energy on earth because it is the earth's (and the solar system's) greatest source of heat and light.

Step-by-step explanation:

The process of photosynthesis in plants uses the energy from the sun and converts that energy to be used for plants.
The burning of fossil fuels produces greenhouse gases which trap the heat in our earth's atmosphere (causing global warming).