Which of the Following Would Cause a Negative Forcing

Multiple Choice

Which of the following would cause a negative forcing?

A) A large volcanic eruption spewing ash high into the atmosphere,blocking sunlight around the world for years until the ash cloud slowly dissipates
B) Snow- covered ice sheets in Greenland melting and revealing bare rock
C) An increase in the burning of fossil fuels,leading to an increase in greenhouse gases in the atmosphere
D) All of these scenarios would cause a negative forcing.