[单选题]

Many modern critics of American literature have called Mark Twain, born Samuel Clemens, ______.
A． as America's greatest writer
B． was America's greatest writer
C． America's greatest writer
D． to have been America's greatest writer

Many modern critics of American literature have called Mark Twain, born Samuel Clemens, ______.A． as America's greatest writerB． was America's greatest writerC． America's greatest writerD． to have been America's greatest writer