Final answer:
March of Progress at Tier 3 allows players to gain 5 bonus experience points per round, but prohibits the use of gold to gain experience points. The change made on 12/8/21 is that it's offered only on the 1st augment choice and the XP per round was increased.
Step-by-step explanation:
The effect of obtaining March of Progress at Tier 3 is that the player gains 5 bonus experience points per round. However, once this power-up is obtained, players can no longer use gold to gain additional experience points. The change that occurred on 12/8/21 regarding March of Progress is that it can now only be offered on the 1st augment choice, and the experience points per round were increased from 4 to 5. Therefore, the correct answer is A) Gain 5 bonus experience points per round. Can no longer use gold to gain experience points.