Binary uses place values that double as you move left. In an eight-bit binary number, the bits from right to left represent 2^0, 2^1, 2^2, up to 2^7. In 10000000, the leftmost bit is 1 and all other bits are 0, so the value is 2^7, which equals 128. The other options correspond to different bit positions: 8 would require a 1 in the 2^3 place; 64 is 2^6; 256 would need a ninth bit (a 1 followed by eight zeros), which is outside eight-bit range.

Code comments are notes in the source code that explain what the code is doing or why certain decisions were made. They’re read by humans, not the computer, so they don’t affect how the program runs. For maintenance, comments are invaluable because they capture the intent behind complex or non-obvious code. They help someone reviewing or updating the program understand why a particular approach was chosen, what edge cases were considered, and what a function expects or returns. This makes it faster and safer to modify the code later, fix bugs, or onboard new team members. Comments should be concise and relevant, providing just enough context to clarify intent without repeating what the code already clearly expresses. Other ideas aren’t about maintaining code: a note that is actually a syntax error would stop the program from running, a function is something the code executes to perform tasks, and a runtime exception is an error that happens during execution. These describe problems or constructs, not helpful documentation for future maintenance.

A variable is a named container in a program that holds data. It points to a location in RAM where a value is stored while the program runs, and that value can be changed as the program executes. The name lets you read or update the data easily—for example, keeping a score or a user’s input and changing it as needed. This differs from a constant, which is a fixed value that never changes, from hardware like a hard drive which is a storage device, and from a function, which is a block of code that does a task and returns a value. So the best description is a named memory location used to store values during execution.

Iteration is repeating a process to improve a solution. When solving a problem, you try something, see how it works, adjust based on what you learned, and try again. Each pass lets you fix mistakes, streamline steps, and move closer to the goal. You keep looping until the result fits what’s required or becomes more efficient. The other options describe things that don’t involve repeating and refining: storing data is just keeping information, a unit of time is a measurement, and a one-time snapshot captures only a single moment.