If \( A = \{x : x \text{ is a letter in word BELOW}\} \), \( B = \{x : x \text{ is a letter in word WOOL}\} \) and \( C = A - B \), then the number of subsets of \( C \) is:
\( 1 \)
\( 2 \)
\( 3 \)
\( 4 \)