__________ transforms source code into the machine-readable code by converting it line by line.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Interpreter
Source code written in a high-level language must be translated into machine code before the computer can run it. An interpreter does this one line (statement) at a time: it translates a line, runs it, then moves to the next, and stops at the first error it meets. Python and BASIC are usually run this way.
Why the other options are incorrect
Option (1) Register — Incorrect. A tiny, very fast storage place inside the CPU that holds the data being worked on; it translates nothing.
Option (2) Compiler — Incorrect. It also translates source code, but the whole program at once into a machine-code file, and lists all the errors together.
Option (3) Cache Memory — Incorrect. A small, fast memory between the CPU and the main memory that keeps often-used data ready.