1. Who led an explor a soldiers from France and Spain
b. Native Americans
c. Meriwether Lewis and William Clark
d. Thomas Jefferson and Napoleon Bonaparte

Complete Question:

Who led an exploration of the land west of the Mississippi River?

c. Meriwether Lewis and William Clark

Explanation:

President Thomas Jefferson of the United States of America, instructed both Meriwether Lewis and William Clark to explore west of the Mississippi River. Also, during the expedition, Lewis and Clark traveled mainly on the Missouri River for the majority of their sojourn in which they traveled for about 8,000 miles. The expedition began on the 14th of May, 1804 till the 23rd of September, 1806; it lasted for two and a half years.

The city where Lewis and Clark began (started) their journey was St. Louis in Missouri and they also ended it in the city of St. Louis in Missouri.

Basically, Lewis was saddled with the responsibility of finding or discovering new animals and plants while Clark was responsible for making maps of the routes they followed.

Hence, Meriwether Lewis and William Clark led an exploration of the land west of the Mississippi River.

the enslaved people onboard suffered from illness with some frequency

this is a good question! i'll do some research and come back when i have the answer!