Explanation:

- The passage discusses the work of speech pathologists within healthcare teams and the different locations where they practice.

- Option 1: "by" typically indicates an agent performing an action or proximity, which doesn’t fit with the passage context describing locations.

- Option 2: "after" implies a sequence or succession in time, which does not address the context of different sites.

- Option 3: "about" often describes the subject of discussion or focus but is unrelated to the context of locations.

- Option 4: "across" indicates being spread over a variety of locations, fitting perfectly with describing the diverse sites where teams work.

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