Explanation:

The act of writing computer instructions in a programming language is universally known as 'coding' or 'programming'. This involves translating human-readable logic and algorithms into a syntax that a computer can eventually process. Option (a) 'assembling' is the process of converting assembly language code into machine code using an assembler. Option (b) 'compiling' is the process of translating high-level source code into machine code or an intermediate form using a compiler. Both assembling and compiling are translation processes that occur *after* the code has been written. Option (c) 'executing' refers to the computer running the program's instructions, which happens *after* the code has been written and translated. Therefore, 'coding' is the most accurate term for the initial act of writing the instructions.