Propan-1-ol is converted into 1-bromopropane with $\mathrm{PBr}{}_3$. The balanced equation shows that

1. A3 mol of alcohol react with 1 mol of $\mathrm{PBr}{}_3$ giving 1 mol of $\mathrm{H}{}_3\mathrm{PO}{}_4$
2. B2 mol of alcohol react with 1 mol of $\mathrm{PBr}{}_3$ giving $\mathrm{H}{}_3\mathrm{PO}{}_4$
3. C1 mol of alcohol reacts with 1 mol of $\mathrm{PBr}{}_3$ giving $\mathrm{POBr}{}_3$ as the by-product
4. D3 mol of alcohol react with 1 mol of $\mathrm{PBr}{}_3$ giving 3 mol of $\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{CH}{}_2\mathrm{Br}$ and 1 mol of $\mathrm{H}{}_3\mathrm{PO}{}_3$