[单选题]
What is the value for the grad1 tk2ky3 bi)nfient of the graph belowu.wqfy q+1o3x with the correct units?
A. Gradient is $\frac{303-183}{25-13}$;Units is dm$^{3}$K$^{-1}$
B. Gradient is $\frac{25-13}{303-183}$;Units is dm$^{3}$K$^{-1}$
C. Gradient is $\frac{183-303}{25-13}$;Units is dm$^{3}$K
D. Gradient is $\frac{13-25}{303-183}$;Units is dm$^{3}$K