Electrons are emitted from a conductor when the conductor is
a. bombarded by high-speed electrons.
b. subjected to a small voltage.
c. cooled rapidly.
d. exposed to weak light.

it should be all of them because it asks if you included all of those in your answer

explanation:

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.