Which option uses parentheses correctly?
A. Mark Twain whose (real name) was Samuel Langhorne Clemens is
a famous American author.
B. Mark Twain whose real name was Samuel Langhorne Clemens is
a (famous) American author.
C. (Mark Twain) whose real name was Samuel Langhorne Clemens is
a famous American author.
D. Mark Twain (whose real name was Samuel Langhorne Clemens) is
a famous American author.