E7F09:Why is an anti-aliasing filter required in a decimator?

Direct answer summary (2024-2028 NCVEC pool)

The official correct answer for E7F09 is It removes high-frequency signal components that would otherwise be reproduced as lower frequency components.

The reason is it removes high-frequency signal components that would otherwise be reproduced as lower frequency components. Connect the cause in the question to this direct result instead of memorizing the answer letter.