Correct answer: B). Food and fossil fuels
The energy can not be created nor destroyed but it can be transformed into another form. The ultimate source of energy on this planet is the sun, the sun provides sunlight where sunlight is converted into chemical energy, which is used by plants to prepare food. Then we consume food prepared by plants to get energy and perform various types of work like movement, reproduction, growth etc. In this, the chemical energy is converted into mechanical energy.