Let $J$ denote the set of of students knowing Java and similarly $P$ and $C$. Now,
$JPC = J + P + C - JP - PC - JC + JPC \\= 54 + 39 + 43 - 15 - 17 - 23 + 11 \\= 92.$
$JPC$ gives the no. of students knowing at least one of Java, Python or C++. So, no. of students not knowing any of these languages
$=100 - 92 = 8.$
Correct Answer: $B$