What is the value of EWMV?

• A. (S_i^2= (x_i-z_i)^2- (1+ ) S_{i-1}^2 )
• B. (S_i^2= (x_i-z_i)^2 (1- ) S_{i-1}^2 )
• C. (S_i^2= (x_i-z_i)^2- (1- ) S_{i-1}^2 )
• D. (S_i^2= (x_i-z_i)^2+ (1- ) S_{i-1}^2 )