A particle has an initial velocity $$3\hat{i} + 4\hat{j}$$ and an acceleration of $$0.4\hat{i} + 0.3\hat{j}$$. Its speed after $$10$$ s is

A

$$10$$ units

B

$$7\sqrt{2}$$ units

C

$$7$$ units

D

$$8.5$$ units