Difficult# Generating Primes

ACTMAT-ENKRCE

Jonathan claims to have discovered a new rule for generating prime numbers. He claims that 1 less than the product of two primes is also a prime (for example, for prime numbers 2 and 3, $2 \times 3 - 1 = 5$, which is a prime).

Which of the following numbers, which can be computed by subtracting 1 from the product of two primes, disproves Jonathan's claim?