Suggest an architecture pattern for the following systems:

1. A ticket machine used by passengers at a bus station.

2. A computer-controlled video conferencing that allows video, audio, and computer data to be visible to several participants at the same time.

3. An image editor. The input is a digital file that processes changes through a series of filters and processing steps.

4. A web-based hospital portal that allows patients to view their records and make minor modifications.

Explain why you chose that architecture pattern.