It seems to me that flight training and private aviation is obsessed with the "rules" of RT and heaps chastisement on anybody who says one word that is different from the RT "Bible". Yes one should learn and endeavor to use the proper phraseology, but not at the expense of effective communication.
Rich g85 made IMO a very fundamental error. He/she acknowledged a transmission they did not fully understand. This is never a good idea. As a student pilot RT instructions may come up that may leave you flummoxed. The best thing to do is to fess up immediately. So in this case an appropriate reply would have been;
"do you want me to go around immediately or descend to 450 feet and then go around ?"
If you are really unsure about what ATC wants simply say
"I do not understand what you want me to do".
Yes it is a bit embarrassing but far better that than an airprox, or worse because you did the wrong thing while trying to sound like a BA 747 Captain on the radio.