What became the primary goal of the Lewis and Clark expedition after t

What became the primary goal of the Lewis and Clark expedition after the conclusion of the Louisiana Purchase in 1803?

A) President Jefferson wanted Lewis and Clark to learn and report back to him and the nation about the lands, native peoples, animals, and plants of the western territory that the United States had acquired and those lands beyond Louisiana Purchase to the Pacific Ocean.
B) President Jefferson wanted Lewis and Clark to confront, report on and, if necessary, kill anticipated hostile Native Americans in the Louisiana territory to clear the way for westward white settlement and U.S. Army forts to be constructed in the newly acquired Louisiana Territory.
C) President Jefferson wanted Lewis and Clark to make it to the West Coast to challenge the Spanish and British claims to the Oregon Territory and Spanish control of California.
D) President Jefferson wanted Lewis and Clark to build forts at strategic points along their expedition that could be eventually transferred to the U.S. Army.

ANSWER
Answer: A