$4.$ It is known that OTP $($one$-$time pad$)$ is secure $($according to its own model$)$ even against a computationally unbounded adversary. Explain why it is impossible for public key encryption to have any meaningful security facing a computationally unbounded adversary. Please describe an explicit attack.

$($Hint: this is true for adversary who does not see any ciphertext, but the public key only$).$