Which is a tool that allows for a number of synchronous and asynchronous…

Concept: Digital tools used in teaching are classed by how learners engage with them in time. A synchronous tool needs the teacher and students present and interacting at the same moment (live video, live chat, a shared board being edited together in real time). An asynchronous tool lets learners access and contribute to material at their own pace, at different times, without everyone being online together. A tool that is described as supporting BOTH must therefore act as a live, real-time collaboration space during a session AND remain a persistent, editable record students can revisit or add to later.

Application: A shared online board — the kind of tool Padlet is — lets a teacher and students post text, images, links, and short audio/video clips instantly during a live class, with everyone seeing new posts appear in real time (the synchronous use). The very same board stays open afterward, so a student who was absent, or one who wants to add a response later, can visit it whenever convenient and contribute or review content at their own pace (the asynchronous use). This dual capability — live collaboration plus anytime-later access — is exactly the requirement in the question.

Cross-check — why each other option fails the same test:

• Textbook: a printed resource whose content is fixed at the time of printing. Unlike a shared online collaboration space, it has no digital, jointly-editable page that can be updated during a live session.

• Railway ticket: a travel document authorising a passenger's seat for a scheduled train journey — it carries no teaching content and has no connection to a classroom exchange of any kind.

• Television: content is produced by a broadcaster and delivered on the channel's fixed schedule, one-way, from broadcaster to audience. Unlike a shared online collaboration space, it has no persistent, jointly editable page that a teacher and students can update and revisit together within the same tool.

Because a shared online collaboration board is the only option here that works as both a live, real-time space and a flexible, anytime-later resource, it is the correct choice.