Comprehensive and Detailed Explanation From Exact Extract:
The algorithm calculates the positive difference between x and y (i.e., |x - y|). According to foundational programming principles, an algorithm's steps must be executed in a logical order, and variables must be declared before they are used.
* Steps Analysis:
* Declare variable Diff: Creates the variable Diff to store the result. Must occur first, as other steps use Diff.
* Set Diff = x - y: Computes the difference, assuming x >= y. Requires Diff to exist.
* If y > x, set Diff = y - x: Adjusts Diff to ensure it's positive if y > x. Requires Diff to exist.
* Put Diff to output: Outputs the final result. Must occur last, after Diff is computed.
* Logical Order:
* Declare Diff (create variable).
* Set Diff = x - y (initial difference).
* If y > x, set Diff = y - x (ensure positive).
* Output Diff.
* Option A: "Put Diff to output." Incorrect. Outputting Diff requires it to be computed, which happens after declaration and calculation.
* Option B: "Set Diff = x - y." Incorrect. Setting Diff requires Diff to be declared first.
* Option C: "If y > x, set Diff = y - x." Incorrect. This step uses Diff, so declaration must precede it.
* Option D: "Declare variable Diff." Correct. Declaring Diff is the first step, as all other steps depend on Diff existing.
Certiport Scripting and Programming Foundations Study Guide (Section on Algorithms and Variables).
Python Documentation: "Variable Declaration" (https://docs.python.org/3/reference/simple_stmts.
html#assignment-statements).
W3Schools: "C Variables" (https://www.w3schools.com/c/c_variables.php).