During RBT training, Linda shows the trainees a video of a client working on a worksheet. She asks the trainees to record the number of times the client goes off-task, which is defined as doing something other than working on the worksheet for more than 10 seconds straight. Trainee 1 records 4 times, trainee 2 records 3 times, and trainee 3 records 2 times. The trainees measurement lacks ______? a) Accuracy b) Validity c) Reliability d) IOA