Answer:
A
Explanation:
The domain of a graph is the set of number you can input for x that will give you a y value. From the looks of it, this graph has all x-values larger than zero.
We know it is not b since we see x-values of the graph go past x=10.
We know it is not c because there are no negative x-values.
We know it is not D because there are no negative x-values. Real number include negative numbers.