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

[EX Q]: Triaxial fabric is woven with _ sets of yarn whose intersections form equilateral triangles.
[EX A]: three

[EX Q]: Pups are unable to swim or find food until seven to _ weeks old or until the ice melts .
[EX A]: eight

[EX Q]: Carbon has _ isotopes.
[EX A]:
two