Final answer:
The prefix 'ante-' denotes before or forward, as in 'antebellum' meaning before the war, and differs from the other listed prefixes like 'anti-' (against), 'ec-' (out of), and 'extra-' (beyond).
Step-by-step explanation:
The prefix that means before or forward is d) ante. The prefix ante- originates from Latin, where it was used to mean before in time or in place. For instance, antebellum refers to the period before a war, particularly the American Civil War, and ante meridiem, which is often abbreviated as A.M., means before midday. The other prefixes listed do not share this meaning; anti- means against or opposite, ec- is a variant of ex- meaning out of, and extra- means beyond or outside.