Answer: Second Option is correct.
Explanation:
Since we have given that
Number of readers = 3
Each of them forwarded the same email to number of readers = 3
So, our equation becomes

Similarly, each of them again forwarded the same email to number of readers = 3
So, our equation becomes

Again each of them forwarded the same email to number of readers = 3.
So, our equation becomes

So, Number of people have read that email is given by

Hence, Second Option is correct.