Idon't know what letters are suppose to go with each other in the colums

Disinfection of impression materials is usually accomplished by a. sterilization with high heat. b. spray or immersion in a chemical disinfectant. c. sterilization with steam under pressure. d. allowing the impression to sit 24 hours in water until all the organisms die.

Which of the following is a way that minerals are used? a. industry construction technology d. all of the above

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?