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

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

[EX Q]: Every earmark consists of a symbol in _ positions.
[EX A]: two

[EX Q]: Polluted water causes diarrhoea, which kills _ million children per year.
[EX A]:
five