Temperature decreases (gets colder) resonant frequencies decreases.. WHY?

3 answers

resonant frequency of what?
If it is a steel guitar string, the tension increases as the wire tries to contract and the frequency increases, not decreases.
However if it is an organ pipe, the air temp decreases and speed of sound decreases and frequency decreases.
The question goes like this:
The original air-filled apparatus now suffers a temp decrease of 40 degrees C, do the resonant frequencies decrease of increase? Give your reasoning
Well, that is my second example above