Match the applications in Column I with the underlying physical reason in Column II.
Column I
P. Gaps left between railway rails
Q. Bimetallic thermostat switch
R. Survival of aquatic animals under ice
Column II
1. Differential linear expansion of metals
2. Maximum density of water at 4 °C
3. Prevention of thermal stress due to expansion
Choose the correct set of matches.
a) P−2,Q−1,R−3
b) P−3,Q−1,R−2
c) P−1,Q−3,R−2
d) P−3,Q−2,R−1