The correct options are
A Erosional landforms are created in the youthful age.
B In the mature stage of the river, the flow is relatively slower than the youthful stage.
C Depositional landforms are created in the old age.
Erosional landforms are created in the youthful age due to the vertical erosion observed in this age. In the mature stage of the river, the flow is relatively slower than the youthful stage. Depositional landforms are created in the old age as the slow speed of the river in this age causes maximum deposition.