Four particles A, B, C and D with masses $$m_A = m$$, $$m_B = 2m$$, $$m_C = 3m$$ and $$m_D = 4m$$ are at the corners of a square. They have accelerations of equal magnitude with directions as shown. The acceleration of the centre of mass of the particles is:

A

$$\frac{a}{5}(\hat{i} + \hat{j})$$

B

$$\frac{a}{5}(\hat{i} - \hat{j})$$

C

$$a(\hat{i} + \hat{j})$$

D

Zero