The following sentences form a paragraph. The sentences are numbered as P, Q, R, S and T. These five parts are not given in proper order. Read the sentences and choose the alternative that arranges them in correct order.

P. For environmental reform, following a massive oil spill off the coast of California.

Q. Drawing attention to the huge challenges facing our planet.

R. Fifty years ago, the first Earth Day was marked in the United States as a peaceful call.

S. Earth Day thus offers an opportunity for us all to reflect upon our relationship with the planet.

T. Half a century later, this annual day unites millions across the globe.