Why Did Anticommunist Harry Truman Veto the McCarran-Walter Act

Why did anticommunist Harry Truman veto the McCarran-Walter Act?

A) The anticommunist measures targeting immigrants did not go far enough for Truman.
B) The McCarran-Walter Act closely mirrored the Committee on Immigration's report, Whom Shall We Welcome, an investigative body commissioned by Truman's political enemies.
C) Truman had become alarmed at the excesses of the anticommunist crusade.
D) Truman did not actually veto the act, preferring to propose an alternative bill.