Each of the following questions consists of six sentences of a passage. The first and sixth sentences are given as S1 and S6. The middle four sentences in each have been jumbled up and labeled as P, Q, R, and S. Find the proper sequence of the four sentences and mark your response accordingly.

S1: Ecological balance means maintaining proper stability with different types of communities and the diversity of organisms which is living on the earth.

P: It is possible on Earth due to the life-friendly atmosphere here and the proper interaction between living and nonliving things. 

Q: To complete the energy requirement, birds eat insects, and these birds are eaten by some carnivorous animals, after that this animal waste and the decomposer of the body merge into the soil and this cycle is going continuously year by year.

R: In earth, all this thing work by a life law of nature which says every element which is present on Earth is taken by someone back to earth after some time. 

S: The engine of this process is sunlight, air, and water which help to continuously run this process.

S6: So we can say in ecological balance, everything has maintained a balance in a natural way.