A two$-$point source interference pattern is generated in a ripple tank. Point $P,$ on the third nodal line, is located $31\mathrm{.}0$ cm from one source and $37\mathrm{.}0$ cm from the other. The wavelength of the waves is

a$.22\mathrm{.}5$ cm

b$.14\mathrm{.}0$ cm

c$.,6\mathrm{.}0cm$

d$.2\mathrm{.}4$ cm

e$.2\mathrm{.}0$ cm