What is the role of heat in the formation of new rocks?

Metamorphic rocks develop when heat and pressure convert an existing rock into a new rock. Contact metamorphism transpires when hot magma converts the rock that it contacts. Regional metamorphism remodels large areas of existing rocks under the enormous heat and pressure created by tectonic forces.

Explanation:

1. (1.2kw)x(15/60hours) = .3kwh --> a

2. (5kw)x(90/60hours)x(8cents/kwh) = $0.60 --> d

3. microwave --> 1200 watts = (1.2kw)x(6/60hours) = .12kwh

coffee-maker --> 900 watts = (.9kw)x(10/60hours) = .15kwh

therefore, it requires more energy for the coffee-maker to do the same amount of work.

so the answer is a.