Which of the following challenges did pioneers typical face on the Santa Fe trail in the mid-1800s

If your choices are the following:

A. desert sand that slowed wagons to a crawl.

B. harsh winter snows that trapped travelers.

C. heavy rainstorms that washed away roads.

D. high, rugged mountains that were hard to cross.

Then the answer is A. desert sand that slowed wagons to a crawl.