In a situation where a player activates an ability, what is the expected sequence of actions?

The correct response details the proper sequence for activating an ability in Magic: The Gathering. When a player activates an ability, they must put the ability on the stack as part of the process. Following this, they must pay any costs associated with that ability for it to resolve successfully. This sequence is essential because abilities often have specific costs that need to be met before their effects can take place.

Activating an ability and placing it on the stack with all associated costs ensures that the game adheres to the structured flow of actions dictated by the rules. This prevents misunderstandings and ensures proper gameplay, as it clearly indicates to other players that the ability is being used and what costs are being paid.

In contrast, the other options do not align with the rules governing ability activation and cause potential issues within gameplay. For instance, revealing a card without using its cost disregards the requirement to fulfill activation requirements; discussing the effect does not align with the structured sequence necessary for gameplay, as abilities generally do not require prior discussion; and announcing an ability without paying costs means the ability cannot be resolved. Thus, following the correct sequence laid out in option B ensures that the game is played fairly and according to its established rules.