If an unexplained variation is 350050 and total variation is 700505, then coefficient of determination would be

3
0.5003
0.7003
2

The correct answer is $\boxed{\text{C}}$.

The coefficient of determination is a statistical measure that is used to determine the proportion of the variation in the dependent variable that is explained by the variation in the independent variable. It is calculated by taking the square of the correlation coefficient.

In this case, the correlation coefficient is $0.7003$. Therefore, the coefficient of determination is $0.7003^2 = 0.5003$.

Option A is incorrect because it is the total variation. Option B is incorrect because it is the unexplained variation. Option D is incorrect because it is not a valid value for the coefficient of determination.