Is the answer d? If not can someone explain

Identify the type of energy used in each action. the flexing of an arm muscle: a signal transduction process by a neuron: a ball at the top of a hill: 1. electrical energy 2. mechanical energy 3. gravitational potential energy

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic

Deserts (especially true deserts) are not easy places for animals to live. animals who live in them often have special features that them survive. which adaptation would be for this group of animals? a) keen eye sight b) short, narrow legs c) tolerate heat d) webbed feet