(1) I sat anxiously yet still in my chair, waiting for the large door to swing open and the dentist’s assistant to shout, "Rachel, Rachel, you’re next!” (2) I was a bundle of nerves and could even hear the rhythmic ticking of the shiny clock above the receptionist’s window. (3) I wondered what the new dentist would be like and hoped he would be as nice as Dr. Jackson. (4) Finally, the door swung open and an unfamiliar man rushed into the waiting room with a brown clipboard, yelling, "Rachel? Rachel, you’re next!” (5) Here we go, I thought as I was herded into the small, yellow-walled examination room and into the large, cushioned reclining chair. (6) Finally, after a few minutes, Dr. Perez casually strolled in and I was pleasantly surprised to be instantly relaxed and comforted by her presence. (7) After a long check-up, Dr. Perez dismissed my unwarranted fears that I might have several deep, cavernous cavities. (8) The walk home was a slow, relaxing, and pleasant conclusion to a long, stressful day.

Which sentence, if added after sentence 6, would best create a strong, descriptive image that helps to explain why Rachel feels comforted?

She was young yet carried herself with great confidence, and her clear eyes locked onto mine and oozed kindness.
Dr. Perez was the youngest-looking dentist I had ever seen. She looked to be only a few years older than me.
I knew that I would like Dr. Perez and would never again be so anxious before a dentist appointment.
Dr. Perez moved quickly around the room, quietly gathering her dental tools.