"A geologist discovers a fault in a massive rock while out in the field. He notices that the fault occurs at an angle and that the hanging wall has moved downward from the footwall. What type of fault has the geologist found?"
a. normal fault
b. reverse fault
c. divergent fault
d. strike-slip fault

normal fault

A fault refers to a planar or curved fracture in the rocks of the Earth crust, in which compressional or tensional forces results in the displacement of the rock on the opposite side of the fracture. Fault may vary in the length of the fracture. A normal fault is a fault in which the hanging wall of the rock moves downward to the footwall. It occurs when the two blocks of rock are separated apart by the tensional forces.  

On the basis of the above information, the normal fault is the fault that should be found by the geologists in the rock.