Fill in the blank with the correct answer from the given options.

This old house is infected ____________ rats.

with

The correct answer is with.

The word with is used to indicate that something is present or associated with something else. In this case, it means that the old house is present with rats.

The other words do not fit the blank as well.

• Along means in the same direction as something else.
• For means intended for or used for something.
• By means near or close to something.