Answer:
C: real number
Step-by-step explanation:
The set of real numbers includes rational and irrational numbers. It would be difficult (impossible) to draw a number line consisting of only rational numbers or only irrational numbers.* So, the number lines we draw represent all real numbers.
_____
* There are an infinite number of rational numbers between any pair of irrational numbers. Similarly, there are an infinite number of irrational numbers between any pair of rational numbers
