Single choice and multiple choice questions helper sentences

I am trying to find the more appropriate helper sentences, e.g. for a single choice question:

"check" only one of the options OR "check" only one of the answers

Is there a better way to say this!?

Also, for multiple-choice questions:

You can "check" more than one option OR You can "check" more than one answer

Can I replace the word "check" with something better? is it ok if I say "Select" instead! I'm open to your suggestions

P.S. this is in a questionnaire context, in a mobile app

Choose or check is fine.

Use may instead of can here.

You may check one answer.

You may check one or more answers.

Or use underlining for boldface.

The word select is just fine; however you might consider the word "populate". This word can be used in multiple choices, short answers and to give any feedback. This is best on an online format.