Question

A) As a wind instrument warms up, the resonant frequencies of the instrument tend to slightly decrease.
B) If the air in a concert hall warms up, the resonant frequencies of the string instruments will change precisely the same as the resonant frequencies of the wind instruments.
C) If you pluck a string one third of the way along its length, you tend to suppress the third harmonic (n=3).
D) If the slide of a trombone is pushed outwards (making the effective tube length longer), all the resonant frequencies of the instrument increase.

I thought the answer was TTFF, but it was wrong. Any idea?