Option A: $\dfrac{1}{30}$
Total numbers from 1 to 30 = 30. Even prime numbers in this range = only 2 (2 is the only even prime). So, P(even prime) = $\dfrac{1}{30}$.
The key fact is that 2 is the only even prime number — all other even numbers are divisible by 2, hence not prime. Students often confuse this and either mark 0 (thinking no even number is prime) or count multiple even primes. Total outcomes = 30, favourable outcomes = 1 (only the number 2), giving $\dfrac{1}{30}$.