The grade of concrete M 150 means that compressive strength of a 15 cm cube after 28 days, is _____.

A

100 $$\frac{kg}{cm^{2}}$$

B

150 $$\frac{kg}{cm^{2}}$$

C

200 $$\frac{kg}{cm^{2}}$$

D

250 $$\frac{kg}{cm^{2}}$$