Question

to prepare for the slippery slide down, riders put on a soft helmet and some arm pads. then they lie on a mat. the mat has a pocket for their feet and a strap to hold as they slide. workers cant secure, or attach, the mat to the rider, so riders must hold that strap tightly all the way down. which of these clues helps you understand what \secure\ means

Explanation:

The word "secure" is followed by "or attach", which is a common way to clarify the meaning of a word (using a synonym or near - synonym as a clue).

Answer:

The clue "or attach" helps understand what "secure" means.