Answer:
Based on the given information, let's try to figure out the seating arrangement. Since there are 3 chairs on each side, we can assume that Adam and Mary are seated on one of the shorter sides of the rectangular table, while Clyde and Benjamin are seated on the opposite shorter side.
Let's consider the possible scenarios:
1. If both Adam and Benjamin are seated on the longer sides:
In this case, Adam is seated on one of the longer sides, and Benjamin is on the opposite longer side. Since Adam doesn't have anyone sitting on his right, the only available option is for Mary to be seated on his left. Clyde and Felix would then be seated opposite Adam and Mary, respectively. However, in this scenario, it is not possible for Ethan to not be seated next to Mary since Ethan would have to be seated between Adam and Mary. Therefore, this scenario is not valid.
2. If Adam and Mary are seated on the same shorter side:
In this case, Mary would be seated on the left end of one of the shorter sides, and Adam would be seated to her right (since Mary doesn't have anyone sitting on her right). Clyde and Benjamin would be seated on the opposite shorter side, with Clyde being on the left end (since Clyde doesn't have anyone sitting on his left). Ethan cannot be seated next to Mary, so he would be seated on the longer side of the table, opposite Adam. Felix would then be seated on the same side as Ethan but to his left, since Felix is the person seated immediately to the left of him.
Therefore, in this scenario, the person seated immediately to the left of Felix would be Ethan.
So, Ethan is seated immediately to the left of Felix.