Question

concession means :
a vote that blocks a decision
the act of taking revenge
a severe shortage
the act of yielding

Explanation:

The word "concession" means giving up something, which is similar to "the act of yielding". "A vote that blocks a decision" is more like a veto. "The act of taking revenge" is retaliation. "A severe shortage" is scarcity.

Answer:

the act of yielding