Sarah’s grandfather takes a nap in his recliner while snoring loudly. When he suddenly stops snoring, Sarah looks to see if he is fine. He appears not to be breathing. For a moment Sarah wonders if he’s dead, but suddenly he coughs and resumes snoring. Sarah’s grandfather appears to suffer from:

Sleep apnea.

Explanation:

Sleep apnea:

Sleep apnea is considered as serious sleep disorder in which patient's breathing during sleep repeatedly stop and start along with snoring.

So, here the scenario that Sarah's grandfather is suffering from sleep apnea because he takes nap on recliner and suddenly stop snoring and stop breathing and again resume the breathing along with snoring.

Sarah’s grandfather takes a nap in his recliner while snoring loudly. When he suddenly stops snoring, Sarah looks to see if he is fine. He appears not to be breathing. For a moment Sarah wonders if he’s dead, but suddenly he coughs and resumes snoring. Sarah’s grandfather appears to suffer from the disorder termed as sleep apnea.                                                                                                  

Explanation:

chordata is the answer

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.