Which sentence uses periods correctly?

a.
mr. aj morris drives to work at 7: 00 am.

b.
mr a. j. morris drives to work at 7: 00 a. m..

c.
mr aj. morris drives to work at 7: 00 a. m.

d.
mr. a. j. morris drives to work at 7: 00 a. m.

Me read the letter. dear aunt mary, you for the wonderful painting. you are so talented! i was thrilled that you chose to paint horses. you must have remembered that i was crazy about horses when i was a little kid—and i still love them. i have hung the painting in my room so that i can see it every morning when i wake up. your loving niece, celia what makes this letter appropriate for its intended audience? it is written from the third-person point of view. it is concise and impersonal. its sentence structure is varied. its language is informal.