Some of the physiographic features that cause extreme aridity may be found together within a <span>single desert, but t</span>he deserts found in the western united states are primarily the result of being located within the rain shadow of one or more mountain ranges.
B. The continents on a map looked like they fit together.
A is the theory he proposed <em>after</em> making this observation
C and D would disprove his theory, not support it.
I could help, however the photo is extremely blurry