If we refer to each of the seven wonders by the first letter of its name, which of these is correct in terms of the order in which they were built?

I'll assume you're talking about the list of Seven Wonders of the World from the ancient world, since we're in the history category here.  I'll list those Seven Wonders in alphabetical order and give the dates for each.  You can take it from there!

Colossus of Rhodes - erected in 280 BC.
Great Pyramid of Giza - construction concluded around 2560 BC.
Hanging Gardens of Babylon - attributed to the reign of Nebuchadnezzar II, 605-562 BC.
Lighthouse of Alexandria - built between 280 and 247 BC.
Mausoleum at Halicarnassus - built between 353 and 350 BC.
Statue of Zeus at Olympia - sculpture created around 435 BC.
Temple of Artemis at Ephesus - actually was built and rebuilt several times; the third version, started in 323 BC, was counted as one of the Seven Wonders.