Final answer:
President Nixon advanced the goal of exiting Vietnam 'with honor' through a strategy that included secretly bombing enemy bases in Cambodia to disrupt North Vietnamese supply lines, which is reflected in Option 4: By attacking enemy bases in Cambodia.
Step-by-step explanation:
The goal outlined in the question was advanced during President Nixon's administration primarily through the strategy of Vietnamization and secret bombing campaigns in Cambodia to target North Vietnamese and Viet Cong bases. This expansion of the war into neutral Cambodia was intended to cut off supply routes and diminish the enemy's capabilities. Accordingly, the option that best advances the goal as stated in the excerpt is Option 4: By attacking enemy bases in Cambodia.
Nixon's administration also saw the normalization of relations with China and strategic maneuvers with the Soviet Union, contributing to an international environment that could pressure North Vietnam. These diplomatic efforts helped to create conditions that made North Vietnam more amenable to peaceful negotiations. Nevertheless, it was the secretive extension of the war into Cambodia that directly aligned with Nixon’s attempts to exert military pressure on North Vietnam while simultaneously reducing American troop presence in the region.