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

[Q]: Planaria has rudimentary eyes which produce _ images but detect direction.
[A]: no


[Q]: Unipolar motors have _ coils and are likely to have five or six wires attached.
[A]: four


[Q]: Most oligochaetes have _ gills or similar structures, and simply breathe through their moist skin.
[A]:
no