a
Frequency of sound heard by car\(-1,\) which comes by reflection from car\(-2\)

\(f _{1}= f _{0}\left(\frac{340+2}{340-2}\right)\left(\frac{340+2}{340-2}\right)\)

\(= f _{0}\left(\frac{342}{338}\right)^{2}\)

Frequency of sound coming directly from car\(-2\)

\(f _{2}= f _{0}\left(\frac{340+2}{340-2}\right)\)

\(\therefore f _{1}- f _{2}= f _{0}\left(\frac{342}{338}\right)\left(\frac{342}{338}-1\right)=8.09 \simeq 8\)