Given the Definite Integral:
You can identify that the interval is:
By definition, if the function is continuous and positive in a closed interval, then:
In this case, you can identify that the function is:
You can graph it using a graphic tool:
Since the closed interval goes from 0 to 1, you need to find this area:
You can identify that you have to find the area of a quarter circle. In order to do it, you can use this formula:
Where "r" is the radius of the circle.
In this case, you can identify that:
Therefore, you get:
Then:
Hence, the answer is: Option D.