The temperature field in a body varies according to the equation $$T(x, y) = x^3 + 4xy$$. The direction cf fastest variation in temperature at the point (1, 0) is given by

A

$$3 \hat{i} + 8 \hat{j}$$

B

$$\hat{i}$$

C

$$0.6 \hat{i} + 0.8 \hat{j}$$

D

$$0.5 \hat{i} + 0.866 \hat{j}$$