Two cars $A$ and $B$ are moving with same speed of $45 \mathrm{~km} / \mathrm{h}$ along same direction. If a third car $\mathrm{C}$ coming from the opposite direction with a speed of $36 \mathrm{~km} / \mathrm{h}$ meets two cars in an interval of 5 minutes. The distance between cars $A$ and $B$ should be (in $\mathrm{km}$ )
(a) $6.75$
(b) $7.25$
(c) $5.55$
(d) $8.35$