Respuesta :
Answer: compulsion
Explanation: Cambridge dictionary describes complusion as a very strong feeling of wanting to do something repeatedly that is difficult to control. Due to the fact that he repeatedly checks his messages every 15 minutes it shows that he is exhibiting compulsive behaviours.
D. Compulsion,because Grayson seems to be so worried about missing someone messaging him that he’s feeling the urge to keep checking his phone. But I would not say it’s an obsession.