Answer:
long strings, less tension, thick strings
Step-by-step explanation:
The frequency produced by guitar string is related with the length, the tension of the string and the linear density of mass. It does not depend on the area of cross section of the string.
The pitch depends on the frequency. Lower frequency means lower pitch.

Where T is the tension, L is the length of the string and m is the mass of the string.
Frequency is inversely proportional to length of wire and directly proportional to its tension.
For lower pitch (lower) frequency, the string should be long and the tension should be less.