Part A: ac + d the result is irrational number
proof,
the product of irrational number with any number apart from 0 is an irrational number
Part B: 4b root 3 + c
the result is irrational number,
proof
root 3 is an irrational number, the product and sum of irrational number with any number apart from 0 is an irrational number
Part C: b^2 (c+d) bthe result is irrational
proof
c+d is an irrational number, b² is rational number, so the result of the product is an irrational number