regular
necessary
dutiful
obligatory
Answer is Right!
Answer is Wrong!
The correct answer is D. obligatory.
The word “obligatory” means required or enforced by law or custom. In this case, the students are required to join the tour. The other options are not as accurate.
- The word “regular” means happening or done at fixed intervals. This does not accurately describe the situation, as the students are not required to join the tour on a regular basis.
- The word “necessary” means essential or indispensable. This does not accurately describe the situation, as the students do not need to join the tour in order to survive or thrive.
- The word “dutiful” means conscientious and obedient. This does not accurately describe the situation, as the students are not necessarily being obedient by joining the tour.
Therefore, the correct answer is D. obligatory.