In 2009, a plague of caterpillars destroyed crops and contaminated water supplies in which country that borders Sierra Leone and Guinea?

The correct answer is Liberia, as it shares borders with both Sierra Leone and Guinea. In 2009, Liberia faced a significant ecological crisis when a large population of caterpillars invaded farmlands, leading to severe crop destruction and contamination of water sources. This event critically impacted agriculture, which is a vital sector for Liberia's economy and food security.

The geographical context of Liberia is crucial, as it directly borders Sierra Leone to the west and Guinea to the north. This regional proximity explains the spread of the caterpillar plague, which likely originated or spread across these borders. The other countries mentioned do not share direct borders with both Sierra Leone and Guinea, making Liberia the only viable choice in this context.