Answer:
C: f(x)=7+5x
Step-by-step explanation:
start replacing 1 in each function and see which one matches:
A gives f(1)=5 so no
B gives f(1)=10, so no
C gives f(1)=12, good
D gives f(1)=17, no again
if you want you can replace the rest of the value to double check, but at least one correct is enough
