a) the original form was *-ilq_wV (which should have yielded PD *-ilq:ʷ- or *-ulq:-, and PA *-i(r)q:ʷ-), but in PD and PA there occurred a contamination with PEC *-iqʷV 'to run' - q.v. This hypothesis is possible, but not very likely, because we have to suppose an independent contamination in two branches (PA and PD);

    b) the original form was *-ilqwV, which regularly yielded PA *-iqʷ- and PD *-ulq-; in PL we should expect *ʔilχʷe-, but this form was avoided because of its homonymousness with *ʔilχʷe- 'to die' (q.v.). For this reason the expected change *qʷ > *χʷ did not happen. This explanation seems more probable, because it involves irregularity only in one branch (PL).