(I) Deciding on how many members a group should
include is problematic for some teachers. (II) In general,
it is safe to say that groups of more than seven students
can be unmanageable since the amount of student
participation obviously falls and disintegration may
occur. (III) Groupwork offers enormous potential
especially for listening tasks, joint reading and
cooperative writing. (IV) But this is not always the case,
and a lot depends on the activity being performed.
(V) Where decisions have to be taken as a result of the
activity, it is a good idea to have an odd number in each
group, but in general tasks, this may not be reasonable.

Which of the sentences in the given paragraph is
irrelevant, violating its unity and coherence?