Concept:
Programming language translators and software categories are important computer concepts.
Step 1:
Compiler converts high-level language into machine-level code.
Thus A is correct.
Step 2:
Interpreter translates and executes program line by line.
It is useful for debugging.
Thus B is correct.
Step 3:
POST and bootstrap loader are system software, not application software.
MS Office is proprietary software, not open source.
Thus C and D are incorrect.
Step 4:
\[
A,\quad B
\]
\[
\boxed{\text{Correct Option = (1)}}
\]