The question below consists of a set of labeled sentences. Out of the four options given, select the most logical order of the sentences to form a coherent paragraph.
P. They are on the market already but they are costly.
Q. Their cost depends on the sort you install and the size of your home.
R. These devices extract warmth from the air or the ground, or from water - a bit like a fridge operating in reverse.
S. Climate advisers anticipate that most homes in future will be warmed by heat pumps.

Correct option is C

The most logical order for the sentences is to first introduce the topic with statement S, followed by a description of the technology with statement R.
Then, address the current cost of the technology with statement P, and finally discuss the factors influencing the cost with statement Q.