The correct option is D Gay-Lussac's Law
From the P vs T graph, we can say that the graph is a straight line passing through the origin.
For an ideal gas,
PV=nRT
or P=(nRV)T ........(1)
Comparing (1) with the equation of a straight line Y=mX+c, we can conclude that P∝T, only when volume is constant, which is the statement of Gay-Lussac's law.
So, option (d) is the correct answer.