What is an interpreter primarily responsible for in programming?

An interpreter plays a crucial role in the execution of programs by translating code line-by-line during runtime. This means that as the program runs, the interpreter reads each line of code, translates it into machine language that the computer can understand, and executes it immediately. This allows for immediate feedback and makes it easier for developers to test and debug their code, particularly in scripting languages like Python and JavaScript.

By contrast, compiling all the code at once, as done by a compiler, involves translating the entire program into machine code before execution. While this approach can lead to optimizations that enhance performance, it does not provide the same level of immediacy and interactivity that an interpreter offers. The options regarding storing code in memory or optimizing code performance are not the primary responsibilities of an interpreter. Instead, they may be associated more with the roles of compilers or memory management systems. Thus, the main function of an interpreter remains the line-by-line translation and execution of code during runtime.