Correct Answer:
C. 25 sq. units
The foundational concept for finding the area of a square is to multiply the length of one side by itself. This is represented by the formula Area = side * side or Area = side2.
Given that the side of the square is 5 units, we apply the formula: Area = 5 units * 5 units = 25 square units. Therefore, option 'C' is the correct answer.
Distractor 'A' (10 sq. units) might be confused with adding the sides (5+5) or multiplying by 2 (2*5). Distractor 'B' (20 sq. units) represents the perimeter (4*5). Distractor 'D' (30 sq. units) is an arbitrary incorrect calculation.