Which of the Following Statements About Alkynes Is Not True $\pi$

Which of the following statements about alkynes is not true?

A) Alkynes undergo many addition reactions.
B) Alkynes are more polarizable than alkenes.
C) Both $\pi$ bonds of a C-C triple bond are weaker than a C-C $\sigma$ bond.
D) The electrons in the $\pi$ bonds of alkynes are more tightly held than those of alkenes.