The correct answer is C. Assembler.
A magnetic tape is a storage medium that uses magnetic tape to store and retrieve digital information. A printer is an output device that prints text or images on paper. A CRT (cathode ray tube) is a display device that uses a cathode ray tube to display images. An assembler is a program that translates assembly language into machine code.
An assembler is not a hardware because it is a program. It is a software that translates assembly language into machine code. Machine code is a set of instructions that a computer can understand and execute. Assembly language is a low-level programming language that is used to write programs that can be executed by a computer.
Magnetic tape, printer, and CRT are all hardware. Magnetic tape is a storage medium that uses magnetic tape to store and retrieve digital information. A printer is an output device that prints text or images on paper. A CRT (cathode ray tube) is a display device that uses a cathode ray tube to display images.