In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

[EX Q]: Pelagic division is divided into neritic and _ levels of pelagic provinces.
[EX A]: three

[EX Q]: Liquid crystals lack the full _ dimensional position and orientation order of ordinary crystals.
[EX A]: three

[EX Q]: All insects have heads, abdomens, and thoraxes, antennae, _ legs, and wings.
[EX A]:
six