Given data

$\vec F = (40\hat i + 10\hat j)\,\text{N}, \qquad m=5\,\text{kg}$

The body starts from rest, so

$\vec u = 0$

Find acceleration using Newton’s second law

$\vec a = \frac{\vec F}{m}$

$\vec a = \frac{40\hat i + 10\hat j}{5} = (8\hat i + 2\hat j)\,\text{m/s}^2$

Use position formula for motion from rest

Since initial velocity is zero and initial position is taken as origin,

$\vec r = \vec u t + \frac{1}{2}\vec a t^2$

With $\vec u=0$,

$\vec r = \frac{1}{2}(8\hat i + 2\hat j)(10)^2$

Calculate components

$\vec r = \frac{1}{2}(8\hat i + 2\hat j)(100)$

$\vec r = 50(8\hat i + 2\hat j)$

$\vec r = (400\hat i + 100\hat j)\,\text{m}$

Match with options

This corresponds to:

Option C: $(400\hat i + 100\hat j)\,\text{m}$

Comparison with stored correct answer

Stored correct answer: C

Our derived answer: C

So they agree.