Explanation:

- Option 1: Section 18

- This section deals with the place of institution of a suit when the jurisdiction is uncertain. It's about the options available if a suit can be instituted in two or more courts where jurisdiction is potentially overlapping.

- Option 2: Section 20

- Section 20 pertains to jurisdictional issues related to where suits should be instituted. It discusses the court's authority based on where the defendants reside or the cause of action arises.

- Option 3: Section 22

- This section deals with the power to transfer suits under the doctrine of convenience from one court to another, provided certain conditions are met.

- Option 4: Section 26

- This is the correct section that deals specifically with the institution of suits. It highlights that every suit shall be instituted by presenting a plaint.