I would say "D" I hope this helps you!
Ending the adjectives with -ed is not needed, so those answers are out. As for the numbers, the rule is usually that numbers one through nine are spelled out whereas number 10 and up are written in numbers. That said, you do not hyphenate the number with the word, so four-letter word would be correct.
The answer is a "cool" don't ask me why but that is what my dad (who works with inmates) said.
Answer:
How could a writer best revise the above sentence to avoid overly formal language?
Explanation:
"Cassidy does not know for which course she will register."