What are the characteristics of a density curve? select all that apply. a. the total

What are the characteristics of a density curve? select all that apply.
a. the total area under the curve is always 1.
b. the curve always falls on or below the horizontal axis.
c. the percentage between any two points is always less than 50%.
d. the percentage of values between any two points is the area of the figure formed by the curve and the horizontal axis.