Which one of the following is reduced with zinc and hydrochloric acid to give the corresponding hydrocarbon

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

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

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

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