Answer:
C. The two middle coefficients multiply to the correct number, but do not add to the correct number.
Explanation:
Question says to factor

Now we need to find about which of the given value pairs can be used as m and n to factor the expression.
Compare
with standard quadratic form
, we get:
a=3, b=-14, c=-5
Then ac=3(-5)=-15
Now we need to find two numbers m and n such that
m*n=ac=-15
and m+n=b=-14
only choice that satisfies above equations is m=-15 and n=+1
But Rahul is using +15x and -1x which will give error addition.
Hence correct choice is C. The two middle coefficients multiply to the correct number, but do not add to the correct number.