If a consumer wishes to opt out of receiving marketing texts from campaign A but still wants to get texts from campaign B, are multiple opt-out options allowed?

Yes, you can have multiple campaigns with their own opt-out requirements, but you should make it very clear to consumers how to do it. For example, text “STOP A” to stop receiving messages from campaign A vs. “STOP B” to stop receiving messages from campaign B. It is also best practice to offer an inclusive opt-out option such as “STOP ALL.”