Ø ∈ {a, b, c} is the correct answer to this question.

Ø represents NULL and an empty set is a subset of every set, that is why the other answer found here (Ø ⊆ {a, b, c}) is a true statement and not the answer to the question.

Ø represents NULL and an empty set is a subset of every set, that is why the other answer found here (Ø ⊆ {a, b, c}) is a true statement and not the answer to the question.