Mark the letter A, B, C, or D on your answer sheet to indicate the best arrangement of utterances or sentences to make a meaningful exchange or text in each of the following questions from 36 to 40.

a. Trainer: Good morning. Can I help you with that?
b. Tam: Oh, it's working. Thank you very much.
c. Tam: Oh, please. I want to change the speed on this treadmill, but I don't know how.
d. Trainer: You can just press this button. Here, let me show you.