Which one of the following compounds will give dimethyl glyoxal with $SeO_2$?

In the Cannizzaro reaction given below:
$2PhCHO \xrightarrow{:\mathop{O}\limits^{\ominus}H} PhCH_2OH + PhC\mathop{O_2^{\ominus}}\limits$
the slowest step is:

Product $C$ is

The compound obtained by the reduction of propionaldehyde by amalgamated zinc and concentrated $HCl$ is

Which of the following compounds gives the Iodoform reaction?

The major product of the following reaction is: