Which of the following are second-order linear homogeneous recurrence relations with constant coefficients? (Select all that apply.)
a) 2ⁿ + 3n
b) a(n) = 2a(n-1) + 5a(n-2)
c) a(n) = 3ⁿ - 2n
d) a(n) = 4a(n-1) - a(n-2)