The correct answer is B.

Explanation: The underlined sound in "think" is the "th" sound, which is pronounced as /θ/.

- B. thesis contains the same /θ/ sound as in "think."

Other options:
- A. that: Contains the /ð/ sound, which is different from the /θ/ sound in "think."
- C. there: Contains the /ð/ sound, which is not the same as the /θ/ sound.
- D. dart: Contains the /d/ sound, which is different from the /θ/ sound.
- E. dark: Contains the /d/ sound and the /ɑː/ vowel sound, which do not match the /θ/ sound in "think."

Thus, "thesis" is the option that contains the sound similar to the one in "think."