A scientist is studying the characteristics of butterflies and collects a random sample of butterflies to measure. Information regarding the wingspan of the butterflies is shown in the histogram below. A histogram titled Butterfly Wingspans has wingspans on the x-axis and frequency on the y-axis. Wingspan of 3 has frequency 6; 3.5, 3; 4, 8; 4.5, 14; 5, 6; 5.5, 3; 6, 5; 6.5, 6.7

Which of the following is a true statement regarding the information shown in the histogram?

Wingspan is a categorical variable.
Wingspan is a discrete quantitative variable.
Wingspan is a continuous quantitative variable.
Frequency is a continuous quantitative variable.