Step 1: Identify the sentence that can stand first.
R names the subject and the main action clearly: "India plans to offer an astronomical site at Hanle". This is a complete, self-contained opening idea, while P, Q, and S are all sentence fragments that depend on something before them.
Step 2: Attach the location detail.
R ends at "Hanle", and Q begins "In Leh for an international collaboration that is", adding the district location and introducing the purpose of the offer. This reads smoothly right after R.
Step 3: Continue the collaboration's purpose.
Q ends with "that is", which needs a present participle to continue describing the collaboration. S supplies "Exploring the possibility of setting up two large gamma-ray", continuing the thought correctly.
Step 4: Complete the list of equipment.
S ends at "gamma-ray", which needs a noun to complete "gamma-ray ___". P supplies "Telescope arrays in the Northern and Southern hemispheres", finishing the sentence about the equipment being set up.
Final Answer:
The coherent order is R, Q, S, P, matching option (c). \[ \boxed{RQSP} \]