Explanation:

High-level programming languages are designed for human readability, but computers only understand machine code (low-level language). To bridge this gap, a translation process is required. Both compilers and interpreters serve this purpose. A **compiler** translates the entire high-level program into machine code before execution, creating an executable file. An **interpreter**, on the other hand, translates and executes the program line by line. Therefore, both compilers and interpreters are tools used to convert high-level programs into low-level programs that a computer can understand and execute. Option (a) 'compiler' is correct, and option (b) 'interpreter' is also correct, making option (c) the most comprehensive answer. Option (d) 'package' refers to a collection of software, not a translator. Option (e) is incorrect as (a) and (b) are valid.