What is Y in the following sequence of reactions?

$\text{2-methyl-2-bromo propane}\underset{\text{dry}\text{ether}}{\overset{\text{Mg}}{\to }}\text{X}\stackrel{{\text{H}}_{\text{2}}\text{O}}{\to }\text{Y}$

Which of the following reactions is used for producing symmetrical alkane with double carbon atoms?

The aldehydes which will not form Grignard product with one equivalent of Grignard reagents are
$\left(\mathrm{A}\right)$

$\left(\mathrm{B}\right)$

$\left(\mathrm{C}\right)$

$\left(\mathrm{D}\right)$

The product formed in the above reaction is