Option 1: What actually has happened -> Ex-post refers to after-the-fact analysis.
Option 2: What actually will happen? -> This is forward-looking, not ex-post.
Option 3: What is actually planned? -> This refers to plans before execution, not ex-post.
Option 4: What should plan be -> This is prescriptive and forward-looking.
Hence, Option 1: What actually has happened -> Ex-post is a Latin term meaning 'after the fact.' It refers to analysis, evaluation, or assessment conducted after an event has occurred, based on actual historical data and real outcomes. For example, ex-post returns in finance are the actual returns that were realized, as opposed to ex-ante (expected or forecasted) returns. -> correct