Which of the following represents a fixed value in source code?

A literal represents a fixed value in source code, and this is why it is the correct choice. In programming, literals are specific values that are explicitly written in the code, such as numbers, characters, strings, or boolean values. For instance, in Java, the number 10, the string "Hello", and the boolean value true are all examples of literals because they directly convey fixed data.

On the other hand, a variable is a named storage location that can hold different values during the execution of a program. It is not a fixed value because the value it represents can change. An operator is a symbol that performs operations on variables and literals, such as addition or subtraction. It does not represent a fixed value itself but rather an action on values. An operand, which can be either a variable or a literal, is what operators act upon. Thus, while operands can be fixed or variable, a literal distinctly denotes a fixed value, confirming why this choice is the correct answer.