How Can an Unfavorable Reaction $\Delta$ G $\degree$ ^' > 0) Still Occur in a Metabolic Pathway

Multiple Choice

How can an unfavorable reaction ( $\Delta$ G $\degree$ ^' > 0) still occur in a metabolic pathway?

A) Link it to another unfavorable reaction.
B) Link it to a favorable reaction.
C) They cannot be used in metabolic pathway reactions.
D) Increase the temperature of the reaction.