Consider an array of length $n$ containing distinct integer values. Which of the following statements regarding the number of comparisons performed by the bubble sort algorithm is true?

a$.$ The number of comparisons is always exactly $n.$

b$.$ The number of comparisons is at most $n-1.$

c$.$ The number of comparisons is at least $n.$

d$.$ The number of comparisons is at most $\frac{n(n-1)}{2}$

Clear my choice