Nitration of propane with concentrated ${\mathrm{HNO}}_3$ gives

$\mathrm{A},\mathrm{B}$ and $\mathrm{C}$ are:

Hence $\mathrm{A}$ is:

The following three isomeric tribromobenzenes are subjected to mononitriation, which is/are gives two mononitrotribromobenzenes:

In the reaction the major product formed is:

The major product formed in the reaction is: