Final answer:
The displacement in the x-direction is 2x.
Step-by-step explanation:
The displacement in the x-direction can be found by taking the partial derivative of the displacement field u = x² + 2y² with respect to x. This derivative will give us the rate of change of u with respect to x. Applying the power rule of derivatives, we can differentiate x² to get 2x. Therefore, the displacement in the x-direction is 2x, which corresponds to option 1.