Answer

The correct sentence:

You can send a pet to an orphanage, although you wouldn’t know it.

In choice “You can send a pet — you wouldn’t know it after an orphanage”, the sentence is illogical.

Note that " Although you wouldn’t know it, you can send a pet to an orphanage " is very similar to " You can send a pet to an orphanage, although you wouldn’t know it ", but it begins the sentence with a dependent clause.