An algorithm is a finite, unambiguous sequence of well-defined instructions for solving a problem or performing a task. The option "Unplug the device, wait 30 seconds, and restart the device" provides a clear, step-by-step procedure to achieve a specific outcome (rebooting the device). Each step is a distinct, executable action, and the sequence is finite, fitting the formal definition of an algorithm.

A. The list contains apples bananas, and oranges: This describes a data structure (a list of items), not a sequence of instructions to perform a task.

B. A webpage uses an HTML file type: This is a statement of fact about a file's property, not a procedural set of steps.

C. The sign of two integers determines the sign of the product: This is a mathematical rule or property, not a step-by-step process for calculation.

1. Cormen, T. H., Leiserson, C. E., Rivest, R. L., & Stein, C. (2009). Introduction to Algorithms (3rd ed.). MIT Press. Chapter 1, Section 1.1, defines an algorithm as "any well-defined computational procedure that takes some value, or set of values, as input and produces some value, or set of values, as output." The example is a procedure.

2. Knuth, D. E. (1997). The Art of Computer Programming, Volume 1: Fundamental Algorithms (3rd ed.). Addison-Wesley Professional. In Section 1.1, Knuth outlines five key features of an algorithm: finiteness, definiteness, input, output, and effectiveness. The provided example meets these criteria.

3. Aho, A. V., Hopcroft, J. E., & Ullman, J. D. (1983). Data Structures and Algorithms. Addison-Wesley. The book's introduction defines an algorithm as "a finite sequence of instructions, each of which has a clear meaning and can be performed with a finite amount of effort in a finite length of time."