If safety stock is 6 and the EOQ is 50, average inventory level is A. 80 B. 86 C. 85 D. 90 E. None of the above

The correct answer is $\boxed{\text{B) 86}}$.

The average inventory level is the sum of the safety stock and the economic order quantity (EOQ) divided by 2. In this case, the safety stock is 6 and the EOQ is 50, so the average inventory level is $\frac{6+50}{2}=\boxed{86}$.

Option A is incorrect because it is the sum of the safety stock and the EOQ. Option C is incorrect because it is the EOQ minus the safety stock. Option D is incorrect because it is the EOQ plus the safety stock. Option E is incorrect because it is not a possible value for the average inventory level.