A data consists of 20 observations $$x_1, x_2, ..., x_{20}$$. If $$\sum_{i=1}^{20}(x_i + 5)^2 = 2500$$ and $$\sum_{i=1}^{20}(x_i - 5)^2 = 100$$, then the ratio of mean to standard deviation of this data is:

A

2:1

B

3:1

C

3:2

D

4:1