In an integrated development environment such as Visual Studio, how do you typically set breakpoints in source code for debugging?

Introduction / Context:
Breakpoints are essential debugging tools that allow developers to pause program execution at specific lines of code to inspect variables and control flow. Modern integrated development environments such as Visual Studio make setting and managing breakpoints straightforward. This question asks how breakpoints are typically set within the editor.

Given Data / Assumptions:
- The developer uses an IDE such as Visual Studio for .NET development.
- Source code is visible in the editor window.
- Debugging features are available, including breakpoints and stepping controls.
- The keyboard and mouse can be used to interact with the editor.

Concept / Approach:
To set a breakpoint, the developer indicates a specific line of source code where execution should pause. Visual Studio supports this by allowing the user to click in the left margin next to a code line, which toggles a breakpoint indicator. Alternatively, the user can place the caret on a line and press F9 to toggle a breakpoint. These actions instruct the debugger to stop when that line is about to execute.

Step-by-Step Solution:
Step 1: Open the source file containing the code you want to debug. Step 2: Locate the line where you want execution to pause. Step 3: Either click directly in the grey margin to the left of the line or place the text caret on the line and press the F9 key. Step 4: Verify that a breakpoint symbol appears in the margin, indicating that the breakpoint is active.

Verification / Alternative check:
After setting the breakpoint, start debugging the application. When execution reaches the marked line, the debugger will pause, highlight the line, and allow you to inspect local variables and call stack. The Breakpoints window can be used to confirm that the breakpoint is registered. Visual Studio documentation describes these same steps, confirming that clicking in the margin or pressing F9 are the standard ways to set breakpoints.

Why Other Options Are Wrong:
Option B is wrong because editing compiled binaries with a hex editor is not how breakpoints are set in a modern IDE and would be extremely error prone. Option C is incorrect since changing the project name has no effect on debugging behavior. Option D is false because file extensions do not control breakpoint placement in the editor.

Common Pitfalls:
A common mistake is setting breakpoints in code paths that are never executed, leading to confusion when the debugger does not stop. Another issue is leaving many breakpoints enabled, which can slow down debugging sessions. Developers should learn to enable, disable, and delete breakpoints as needed using the editor margin and the Breakpoints window for efficient debugging.

Final Answer:
You typically set a breakpoint by clicking in the left margin next to a line of code or by placing the cursor on that line and pressing F9, which toggles the breakpoint in Visual Studio.