In a 2-level factorial design with 5 factors, the total number of possible combinations is 2^5 = 32. If the design is using 16 experimental runs, it indicates a half-fractional factorial design. Therefore, Statement A is correct. Main effects in half-fractional designs are typically confounded with higher-order interactions depending on the design, so Statement B and C can be correct under such circumstances. However, Statement D is incorrect because, in a half-fractional design, each level of a factor should appear equally often across runs. Hence, it is impossible for 8 experimental runs to have the first factor consistently at the high level without skewing the design balance.