The whole nation was ____ the president.

The correct word to complete the sentence “The whole nation was ____ the president” is “behind.” This choice implies support and alignment with the president’s actions or policies. When a nation is “behind” someone, it means they are giving their full support, agreement, or loyalty to that person or cause. This preposition indicates a collective endorsement, suggesting unity and backing.

• Option A, “against,” is incorrect because it would mean the nation was in opposition to the president, which is the opposite meaning of what the sentence aims to convey in a supportive context. If the nation were against the president, it would indicate widespread disapproval or resistance.
• Option C, “front,” is incorrect as it does not grammatically or contextually fit into the sentence. “Front” is usually a noun or an adjective, and its use here would make the sentence nonsensical, as it doesn't convey a relationship of support or opposition.
• Option D, “besides,” is incorrect because it means in addition to or apart from. If the nation were “besides” the president, it would simply mean they were next to him or not part of the same group, which does not convey support.