The general equation for a straight line is
y = mx + c
where
m = slope
c = y-intercept
The line passes through the origin (0,0), therefore
0 = m*0 + c => c = 0
Therefore the equation is of the form
y = mx
The line passes through (1,3). Therefore
3 = m*1 => m = 3.
The equation for the line is
y = 3x
Answer: C) y=3x
