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).
