Question $24($Mandatory$)(4$ points$)$

$($Show your work$)$ If Oscar wishes to carry out a brute$-$force attack on a block cipher

with a key length of $56$ bits and $50-$bits blocks of plaintext$-$ciphertext, and Oscar

checks $2-$ plaintext$-$ciphertext pairs. What is the expected number of false positive

results in this scenario?

A$)1$

B$)2^{-1}$

C$)2^{-44}$

D$)2^{34}$