How does a stream typically change as it flows from its headwaters to its mouth?
a. discharge decreases, channel shape widens
b. gradient increases, channel shape narrows
c. gradient decreases, discharge remains the same
d. gradient decreases, discharge increases

D. Gradient decreases, discharge increases.

Explanation:

As steam is a body of water that carries rock particles and dissolved ions,  discharge is measured in terms of volume/time (m3/sec).  So when a river discharges its flow from a headwater to its mouth the velocity increases in the downstream direction. Thus the river load-carrying capacity increases downwards and so does the discharge rate. The discharge rate can also be influenced due to the rainfall patterns, volume of water and velocity of flow. Rock types also impact the streamflow if it is a porous rock, the surface will absorb more of moisture content and comparative more will be the water penetration towers the mouth of the flow.