Nuclear fusion
a. takes place in the sun
c. can be controlled in the laboratory
b. occurs at low temperatures
d. is used in medicine

Nuclear fusion takes place in the sun, letter A. The sun is a ball of hot gases. Initially, it contains hydrogen and helium. When they fuse together, it forms carbon. After carbon, nitrogen, oxygen silicon follows until it forms a massive hot ball of gases. The net result is the fusion of four protons into one alpha particle with the release of two positrons, two neutrons and energy.

neither accurate nor precise.