Which of the following statements are true?

a. All files are stored in binary format. So, all files are essentially binary files.
b. Text I/O is built upon binary I/O to provide a level of abstraction for character encoding and decoding.
c. Encoding and decoding are automatically performed by text I/O.
d. For binary input, you need to know exactly how data were written in order to read them in correct type and order.

abcd