#lookahead-leakage

Question 1: Single choice

You forecast Monday's sales of school supplies. The series onpromotion counts the items on promotion each day, and the company plans its promotions in advance. May you use Tuesday's onpromotion value as a feature in Monday's forecast?

Yes; it is known when the forecast is made, so nothing leaks1
No; any value dated after the forecast target leaks information from the future2
No; only lagged values of the target series itself can be used as features3
Yes, but only after the promotion series has been deseasonalized4

Timed test