The answer is D. "She filled her living room with dozens of tulips."
A is incorrect. It should either say "Seven thousand people showed up for the concert," or "Thousands of people showed up for the concert."
B is incorrect since hundred is used, and not the plural form, hundreds. The correct form would be: "He needed hundreds of quilt squares for this project."
C is also incorrect. The correct way to write the sentence would be: "Does anyone know why Steve ordered five dozen eggs?"