The modulo operator (%) returns the remainder of an integer division. In a base-10 number system, dividing any integer by 10 yields a remainder equal to its rightmost digit. For the integer q = 16222, the expression q % 10 calculates 16222 / 10, which is 1622 with a remainder of 2. Therefore, q % 10 evaluates to 2, the rightmost digit.

A. q / 100000 is integer division, resulting in 0, as 16222 is less than 100000.

B. 10 % q calculates the remainder of 10 divided by 16222, which is 10, not the rightmost digit of q.

D. q % 10000 calculates the remainder of 16222 divided by 10000, which is 6222.

1. International Organization for Standardization. (2011). ISO/IEC 14882:2011 Information technology — Programming languages — C++. Section 5.6, "Multiplicative operators," defines the % operator as yielding the remainder from the division of the first expression by the second.

2. Oracle. (n.d.). Primitive Data Types. The Java™ Tutorials. Retrieved from https://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html. This documentation describes the remainder operator % for numeric types.

3. Harvard University. (n.d.). CS50x 2024: Lecture 1 - C. Section on "Operators." The lecture explains how i % 10 can be used to get the last digit of an integer i.