Hello M7MBA.

Let's take a look at your question.

We have one prime number "a" that is greater than 2 and less than 6. Hence a=3, 5.

The other primer number "b" is greater than 13 and less than 25. Hence b=17, 19, 23.

Hence, the possible products are:

If a=3 then

if b=17-------------------a*b=51.
if b=19-------------------a*b=57.
if b=23-------------------a*b=69.

If a=5 then

if b=17------------------a*b=85.
if b=19------------------a*b=95.
if b=23------------------a*b=115.

Therefore the correct answer is the option [spoiler]E=51[/spoiler].

I hope it helps you.

I'm available if you'd like a follow-up.

Regards.