Answer:
D. ∠ABC
Explanation:
We are given a figure consisting of rays AB, CB and DB having a common end point B.
It is required to find the value of 1 marked in the figure.
As, we can see, 1 is representing the region between the rays AB and CB.
We know that, an 'angle' is a figure that joins two rays having one common end-point.
This gives that 1 represents an angle between AB and CB.
So, 1 is ∠ABC.
Hence, the correct letter for 1 is D.