Which of the following is written correctly?
.A
Vlad’s room in America was bigger than his old room, but school was more challenging because he did not know the language.

B.
Vlad’s room in America was bigger than his old room, but school was more challenginger because he did not know the language.

C.
Vlad’s room in America was biggest than his old room, but school was more challenging because he did not know the language.

D.
Vlad’s room in America was more bigger than his old room, but school was more challenging because he did not know the language.