The Length of a Pendulum Changes by Thermal Expansion $\sqrt{1.001}$

Multiple Choice

The length of a pendulum changes by thermal expansion. If the length increases by 0.1%, what would be the change in the period?

A) increase by $\sqrt{1.001}$
B) increase by 0.1%
C) decrease by 0.1%
D) decrease by 0.99