Hot coffee in a mug cools over time and mug warms up. Which describes the energy In this system

Two changes are described below. a green banana turns yellow and ripens. a layer of rust forms on an iron nail. which statement is true about the two changes? a) both are chemical changes because new substances are formed. b) both are physical changes because only the physical state of the substances change. c) a is a physical change due to a change of state, but b is a chemical change because new molecules are formed. d) a is a chemical change due to a change of state, but b is a physical change because new molecules are formed.