Ahot air balloon descends to the ground. the function h(t) = 210 – 15t can be used to describe the altitude of the balloon as it approaches the ground. which statement best describes the graph of the function that models the descent of the balloon?

a) the graph is discrete because there cannot be fractional values for time.
b) the graph is discrete because there cannot be negative values for altitude.
c) the graph is continuous because there can be fractional values for time.
d) the graph is continuous because there can be negative values for altitude.