Answer:
D) 5
Step-by-step explanation:
Perpendicular lines have opposite reciprocal slopes.
The line:
has a slope of
as it is in y=mx+b form, where m is the slope, and b is the y-intercept.
Since the slope is
, we see that the negative reciprocal slope is
, as
is the reciprocal (flip the numerator and denominator).
From here, we can use point slope form:
, where
is the point. In this case, (3, 1) is the point.
Thus, we have:
as our final equation.
Simplifying: 
And:
, which gives us the y-intercept to be 5.
Let me know if this helps!