h of the following are frequently encountered problems when collecting cost data on variables included in a cost​ function? A. 1. The time period used to measure the dependent variable is not properly matched with the time period used to measure the cost​ driver(s). 2. Fixed costs are allocated as if they are variable. B. 1. Data are either not available for all observations or are not uniformly reliable. 2. Extreme values of observations occur. C. 1. A homogeneous relationship between the individual cost items in the dependent variable cost pool and the cost​ driver(s) does not exist. 2. The relationship between the cost and the cost driver is not stationary. D. All of the above are correct.