Which of the Following Was Not Part of President Richard

Which of the following was not part of President Richard Nixon's strategy in Southeast Asia?

A) escalated American bombing of North Vietnam.
B) ordered massive increases in American ground forces to invade North Vietnam.
C) replaced American troops with South Vietnamese forces.
D) opened secret direct negotiations with North Vietnam's foreign minister, Le Duc Tho.
E) widened the war by invading Cambodia.