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

[EX Q]: Tetrachoric correlation is _ artificially dichotomous variables.
[EX A]: two

[EX Q]: Prostate cancer has _ symptoms in the early stages.
[EX A]: no

[EX Q]: Malignant tumors are more dangerous, and survival times can range from _ months to several years.
[EX A]:
six