(1) Gretchen searched around looking for her missing keys. (2) She thought she had seen them in the kitchen. (3) When she looked around all over. (4) They were not there. (5) Then she checked under the couch seat cushions, and there they were! (6) She was very relieved.

Which of the following is a sentence fragment?

A. sentence 4

B. sentence 3

C. sentence 6

D. sentence 5​