Please suggest which option is correct
1. He studies in ______ sixth grade.
a. no article b. a c. an d. the
Some suggests no article and some suggests the
Americans would probably "He's in sixth grade" more often than "the sixth grade.". You'll hear both.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.