Cyclobutyl bromide on treatment with magnesium in dry ether forms an organometallic compound `(A)`. The organometallic compound `(A)` reacts with ethanal to give an alcohol `(B)` after mild acidification. Prolonged treatment of alcohol `(B)` with an equivalent amount of `HBr` gives 1-bromo-1-methylcyclopentane ( C) Write the structures of `(A)` and `(B)`, and explain how `(C)` is obtained from `(B)`.

Explanation