Let $H,H^{\text{'}}$ be collision$-$resistant hash functions. Which of the following functions $H^{\text{'}\text{'}}$ is NOT necessarily collision$-$resistant?

$1$ point

$H^{\text{'}\text{'}}(x)=H(H^{\text{'}}(x)).$

$H^{\text{'}\text{'}}(x)=H(x)||0$dots$0,$ where $||$ denotes concatenation.

$H^{\text{'}\text{'}}(x)=H(x)||H^{\text{'}}(x),$ where $||$ denotes concatenation.

$H^{\text{'}\text{'}}(x)=H(x)o+H^{\text{'}}(x)$