Consider RSA with p = 31 and q = 47. I. n = 1457 II. z= 1200 III. 7 is acceptable choice for e

Which of the following is true ? A. Only I B. Only I and II C. Only I and III D. All of I,II and II

I am Getting answer (C), but answer is given (D).

As per kurose Ross, Z is defined to be $(p-1)(q-1)$

You don't need $d$ to calculate $e$. In fact, it's using $e$, that we calculate $d$. The only condition for $e$ is that $gcd(e, \phi(n)) = 1$ @srestha

yes

but we should know one of $d$ or $e$

rt?

7 is acceptable choice for e

this is not correct

because it might happen 5,3 also acceptable for e