Hich one of the following sentences contains an incorrect usage of the singular possessive? a. the north forty has always been my family's land. b. mary was dominant among jesus' disciples. c. the alpha male is often the pack's leader. d. icarus's fate was sealed when he approached the sun.

The correct answer (that is, the incorrect usage) would be B. Mary was dominant among Jesus' disciples. In most cases, singular possessive has an apostrophe followed by s even when the name ends in -s. So, in this case, the corrected form would be "Jesus's disciples" just like it's "Icarus's fate" in the last sentence. This rule has only one exception: when this -s at the name's end is not pronounced (as in some French names, e.g. Rabelais).

B. Mary was dominant among Jesus' disciples.