What occurs when a syntax error is present in a piece of code?

When a syntax error is present in a piece of code, the program fails to compile. A syntax error occurs when the code violates the grammatical rules of the programming language, such as incorrect punctuation, spelling, or structure. This prevents the compiler or interpreter from understanding what the programmer intends to do, leading to a failure in the compilation process. As a result, the code cannot be executed until the syntax error is corrected.

The other consequences presented by different choices pertain to other types of issues in programming. Running slower is often associated with performance problems rather than syntax errors. Logical flaws and unexpected output relate to semantic errors, which occur when the syntax is correct but the logic does not produce the desired results. Thus, option B accurately describes the fundamental consequence of encountering a syntax error in code.