In this Set 2 question , here value of air pressures are :-
P = 0.95 , Q= 0.8 , S = 0.95 , R= 0.65
now the possibility of thunderstorm says how fast the value rises or how quickly the value drops .
P and S have same value. i can obsolete these 2 options.
So now only 2 options left , among them Q have average value .
Only R have Minimum value , now only Minimum Value can drop quickly , hence R can be the region have most likely to get a thunderstorm.
Which is option C .