5. What completed the map of the continental United States as it is today? O Louisiana Purchase
O Mexican Cession
O Gadsden Purchase
O annexation of Texas

Correct answer is Gadsden Purchase.

Explanation:

Gadsden Purchase is the correct answer as according to it United States in 1854 gained a territory that later became a part of Arizona and New Mexico.

Louisiana Purchase is not correct as this is actually the first step towards the westward expansion.

Mexican Cession was a term used after the treaty of 1848 when US gained territories in the south.

Annexation of Texas happened in 1845, and according to it Texas became a part of US.