For All the Allowed Vibration(s) (Wavelength(s)) of a Plucked Guitar $\lambda$

For all the allowed vibration(s) (wavelength(s) ) of a plucked guitar string, what is the correct relationship between the length of the string, L, and the wavelength, $\lambda$ ?

A) L = $\lambda$ /2
B) L = $\lambda$
C) L = n $\lambda$ /2 where n is a positive integer
D) L = n $\lambda$ where n is a positive integer
E) L = 1/ $\lambda$