[单选题]
When the mass of a sim4m-4lwxrwmmfdkm83 *5 (vi2n 6kujav pmp/jl)j3zc5 n)z x6rf le pendulum is tripled, the time required for one complete vibrationlz6z rn5j)/f)mpcx3 j
A. increases by a factor of 3.
B. does not change.
C. decreases to one-third of its original value.
D. decreases to 1/3 of its original value.
