The differential equation dy dx equals the quotient of the quantity x minus 3 and x plus 4

Question

The differential equation 

1. produces a slope field with horizontal tangents at x = −4
2. produces a slope field with vertical tangents at x = −4
3. produces a slope field with columns of parallel segments

I only 

II only 

I and II

 II and III only

Answer 1

dy = (x-3)/(x+4)

slopes are undefined at x=-4, so vertical tangents at x=-4

slopes are zero at x=3, so horizontal tangents at x=3