"Gather" and "assemble" are good. "Collect" is acceptable. The others are not good. "Muster" is a military word. It would not be used for students unless they were cadets. "Call together" doesn't make sense at all, because who would the students be calling?

Let's look at how each word fits the blank: Original sentence: All the students were asked to ____ in the main hall. 1. Gather ✅ Fits well. "Gather" is commonly used when people are asked to come together in one place. It emphasizes bringing people into a group. 2. Collect ❌ Doesn't fit naturally. "Collect" usually refers to gathering objects rather than people. When used with people, it suggests an impersonal or even forceful action, which would be unnatural here. 3. Muster ✅ Fits, but more formal or specific. "Muster" often implies assembling people for a purpose, such as a military roll call or important event. It works here but gives the sentence a more serious tone. 4. Assemble ✅ Fits well. "Assemble" is formal and suggests an organized gathering, often for a specific reason. It’s commonly used in academic or official contexts. 5. Call together ✅ Fits, but more informal. "Call together" implies someone has summoned or invited the group to meet. It sounds a bit more casual or conversational compared to "assemble." Summary: Best choices: "Gather," "assemble," and "call together" fit naturally in the sentence. Context-dependent: "Muster" works well in formal or serious settings. Avoid: "Collect" doesn’t work naturally for people in this context.