The number of prime numbers having two digits in which the digits are also prime is

Correct option is A

Given:

Number of two-digit prime numbers such that both digits are also prime.

Solution:

Two-digit numbers formed using prime digits (tens and units both prime):
22, 23, 25, 27
32, 33, 35, 37
52, 53, 55, 57
72, 73, 75, 77

Now check which of these are prime numbers:

23,  37, 53, 73

All others are composite.

Total such numbers = 4