As you know that (D,/) is a POSET (partially ordered set) if it fulfills three properties of,
In addition to these, if all elements in your set also are comparable with each other.all element in a set are comparable with respect to division operator then POSET is TOSET.
Option A ALL element are comparable with respect to division operator ( 6 divided by 2,24 divided by 6 and 2).
option B Here 3,5 are not comparable (5 not divide by 3 or 3 not divide by 5)
option C Here (2,9 ),(16,9) are not comparable (9 not divide by 2 or 16 not divide by 9)
option D Here (4,15),(4,30) are not comparable (15 not divide by 4 or 30 not divide by 4)