Which musical device can composers use to lengthen a note by double?

staccato

tenuto

marcato

fermata

rubato

Tenuto is the answer

The correct answer here would be fermata. This is a musical notation that is also known by numerous names such as a hold, a pause or my personal favorite the cyclops eye. This notation is used to indicate that a note should last longer than its normal duration. And that includes doubling its duration.