___ you're late, I will be angry.

• A. If
• B. When
• C. Unless
• D. Because

Answer: (A)

This sentence tests choosing the right conditional for a possible future outcome. When you want to talk about a future result that depends on a real, possible condition, you use the first conditional: if + present simple, will + base verb.

Here, the condition is being late (present simple). The result is a future reaction: I will be angry. This makes sense as a warning about what could happen if the condition occurs. Using when would imply lateness is certain or habitual, which changes the nuance. Using unless would flip the meaning to something like “I’ll be angry unless you’re late,” which doesn’t fit the intended idea here. Using because would present a reason for anger rather than a conditional future outcome.

So the best choice is the word that introduces a real, possible condition: If.