Which of the following questions might best be answered by the method of hypothesis-based science?

a) how many kinds of tissues make up the kidney?
b) do humans beings have free will?
c) how many leopards inhabit the sabin sands reserves in southern africa?
d)are there diseases that are caused by evil spirits
e) does vitamin biotin prevent birth defects

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.