TASK DEFINITION: In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
PROBLEM: Excess potassium induces larval metamorphosis in _ marine invertebrate species.

SOLUTION: four

PROBLEM: Bacteriophage lambda has _ different life cycles.

SOLUTION: two

PROBLEM: Marriage is the bringing together of the _ sexes.

SOLUTION:
two