Answer:
Water travels through the passages in a manner that is similar to water flowing through pipes in a plumbing system.
Explanation:
In the passage, the author has compared the geysers' plumbing system with the underground water-filled boiling water as the movement of the water in passages are similar to the course of water through pipes in the plumbing systems.
The writer in this passage is talking about the fickleness of the geysers. The writer supports it by saying that this fickleness is because of the frequent changes that an underground passage goes through, which is filled with boiling water.
<u>The current of water in both the passages and the pipes are similar, this is why the writer used the reference of 'geysers plumbing system.'</u>
Thus the correct answer is the second option.