Coefficient of volumetric expansion is not constant and is . . .

Question : Coefficient of volumetric expansion is not constant and is dependent on temperature. The coefficient of volumetric expansion with temperature for copper varies as : 






Doubt by Yathatha & Zoha
DAV 2023

Solution : 

Coefficient of Volume Expansion (αV
[We have denoted it by γ in our class notes.]
ΔV = αVVΔT
ΔV/V = αVΔT
The graph can be interpreted by a complex logarithmic and exponential relation, which out of the scope of this class. 
By the way, the graph is directly from the NCERT Chapter - 11 (Thermal Properties of Matter). You can check Physics Class 11 NCERT Part - 2, Page No 277 & Figure No. 11.6


Hence, c) is the correct option.