Bats can detect small objects such as insects that are of a size approximately tht of one wavelength. If bats emit a chirp at a frequency of $60$ kHz$,$ and the speed of sound waves in air is $335$ m$/$s$,$ what is the smallest size insect they can detect?$9$A$)6\mathrm{.}6$ mm$12$B$)5\mathrm{.}6$ mmC $4\mathrm{.}6$ mm$1415$D$)3\mathrm{.}6$ mm