The question would be SO much easier to answer if we could
SEE the graphed function, or even just its equation.
5/ sqrt (10)
no radicals in the denominator so we multiply by sqrt(10)/sqrt(10)
5/ sqrt (10)* sqrt(10)/sqrt(10)
5 * sqrt(10)
---------------
10
sqrt(10)
-----------
2
I took a look at the picture and the right answer for this question would be A