the complete question in the attached figure
we have that
(3/4)
case a)
6/12--------> divided by 6 both members--------> 1/2
then
6/12 is not equivalent to 3/4
case b)
9/12--------> divided by 3 both members------> 3/4
then
9/12 is equivalent to 3/4
case c)
12/20-----> divided by 4 both members-----> 3/5
then
12/20 is not equivalent to 3/4
case d)
18/20------> divided by 2 both members-----> 9/10
then
18/20 is not equivalent to 3/4
the answer is
The other ratio equivalent is the option b) 9/12