Answer:
C
Explanation:
y = 2x + 5
the slope (m) of this line is 2 (which can be written as 2/1)
The slope of a perpendicular line is -1/m (the reciprocal of the slope with the opposite sign)
so m = 2/1 => -1/m = - 1/2 = the slope of a line perpendicular to y = 2x + 5