Answer: WST, WGF, WSC, WGT
Explanation:
As each sandwich consists of one type of bread, one type of cheese, and one type of meat, there must be one letter out of W, I and B. There must be one cheese and there must be one letter out of G and S. There must be one meat and there must be one letter out of C, T, F and H.
The possible combinations must include three letters. Thus WSTWG, WS, WC, WTWGT, WSHWGSC and WGSF could not be the right choices.
The possible combinations are WST in which W is for wheat bread, S is for sliced cheese and T is for turkey meat.
WGF, in which W is for wheat bread, G is for grated cheese and F is for fish meat.
WSC, in which W is for wheat bread, G is for grated cheese and F is for fish meat.
WGT, in which W is for wheat bread, G is for grated cheese and T is for turkey meat.