Consider the following Python code snippet.
\[
A = \{\text{"this"}, \text{"that"}\}, \quad B = \{\text{"that"}, \text{"other"}\}, \quad C = \{\text{"other"}, \text{"this"}\}
\]
\[
\text{while "other" in C:}
\]
\[
\quad \text{if "this" in A:}
\]
\[
\quad \quad A, B, C = A - B, B - C, C - A
\]
\[
\quad \text{if "that" in B:}
\]
\[
\quad \quad A, B, C = C | A, A | B, B | C
\]
When the above program is executed, at the end, which of the following sets contains "this"?