1 A matrixing design should be __ so that each combination of factors is tested to the same extent over the intended duration of the study and through the last time point prior to submission 2 All selected factor combinations should be tested at the __ time points 3 For matrixing at an accelerated or intermediate storage condition, __ should be taken to ensure testing occurs at a minimum of three time points, including initial and final, for each selected combination of factors