I would like clarification on a question on the Skin Type Questionnaire.

Question #12 on the Wrinkled vs. Tight Questionnaire is not clear to me.

As it states " During the last five years, how often have you allowed your skin to tan either intentionally or unintentionally through outdoor sports or other activities?"

The answers are
a. Never
b. Once a month
c. Once a week
d. Daily

There is nothing in between "Never" and "Once a Month".
I may have intentionally tanned once or twice a year over the last five years, so I do not know how I should answer.

Thanks for your help!