Consider the following reaction sequence. $(A)$ and $(C)$ are

$$ \mathrm{CH}_3 \mathrm{CHO} \xrightarrow[\text { (ii) } \mathrm{H}_2 \mathrm{O} / \mathrm{H}^{+}]{\text {(i) } \mathrm{CH}_3 \mathrm{MgBr}}(A) \xrightarrow{\mathrm{H}_5 \mathrm{SO}_4 . \Delta}(B) \xrightarrow[\text { (ii) } \mathrm{H}_2 \mathrm{O}, \mathrm{H}_2 \mathrm{O}_2 / \mathrm{OH}^{-}]{\text {(i) } \mathrm{B}_3 \mathrm{H}_6}(C) $$

Identify the end product $(Z)$ in the sequence of the following reactions.

What is ' $Z$ ' in the given sequence of reactions?