Rearrange the parts of the sentence in the correct order.
North India
P: needs a more holistic solution
Q: to the toxic air that residents
R: breathe at the onset of winter

Let's join the sentence segments step-by-step beginning with the subject "North India":
North India links to the verb phrase P (needs a more holistic solution).

The solution is needed for something, which is logically followed by Q (to the toxic air that residents).

The clause finishes with what residents do to that air, which is R (breathe at the onset of winter).

Combining them gives: "North India needs a more holistic solution to the toxic air that residents breathe at the onset of winter."
The correct sequence is PQR.