S1: There is no transportation system in any city that can compare in efficiency with the circulatory system of the body. P: The larger one goes from the heart to the various other parts of the body. Q: If you imagine two systems of pipes, one large and one small, both meeting at a central pumping station, you’ll have an idea of the circulatory system. R: These pipes are called arteries, veins and capillaries. S: The smaller system of pipes goes from the heart to the lungs and back. S6: Arteries are blood vessels in which blood is going away from the heart. The Proper sequence should be: A. PQSR B. QSPR C. RSQP D. SPRQ

The correct answer is A. PQSR.

The first sentence, S1, introduces the topic of the paragraph, which is the circulatory system. The second sentence, P, provides a simile to help the reader understand the circulatory system. The third sentence, Q, provides more detail about the circulatory system. The fourth sentence, R, provides more detail about the circulatory system. The fifth sentence, S, provides more detail about the circulatory system. The sixth sentence, S6, provides more detail about the circulatory system.

The correct sequence of the sentences is PQSR. This is because the second sentence, P, provides a simile to help the reader understand the circulatory system. The third sentence, Q, provides more detail about the circulatory system. The fourth sentence, R, provides more detail about the circulatory system. The fifth sentence, S, provides more detail about the circulatory system. The sixth sentence, S6, provides more detail about the circulatory system.

The other options are incorrect because they do not follow the logical order of the sentences. Option B, QSPR, is incorrect because it does not start with the simile in sentence P. Option C, RSQP, is incorrect because it does not start with the sentence that provides more detail about the circulatory system in sentence Q. Option D, SPRQ, is incorrect because it does not start with the sentence that provides more detail about the circulatory system in sentence R.