How did President Thomas Jefferson's actions affect Manifest Destiny? A.) He slowed westward expansion when two economic depressions occurred during his presidency.

B.) He sped up westward expansion with the Louisiana Purchase and the expedition of Lewis and Clark.

C.) He slowed down westward expansion by allowing Spain to keep Texas when he negotiated to obtain Florida.

D.) He sped up westward expansion by signing a treaty with Great Britain regarding the Oregon Territory.