F
The basic F chord is another chord which is often substituted. Like the basic D chord the standard alternating bass line is between the third and fourth strings making it impossible to allocate the third string to the right hand fingers.
A popular alternative to using the basic F chord is to use the F bar chord as shown. By substituting the F bar chord it is possible to use the sixth and fourth strings as bass notes thus allowing the right hand fingers to play the third string.