Which of the following statements are not true?
(a) Sum of two irrational numbers is always irrational
(b) Difference between two irrational numbers is irrational
(c) Product of two irrational numbers is irrational
(d) Quotient of two irrational numbers is irrational
(A) (a) and (b) only
(B) (a), (b), (c) and (d)
(C) (a), (b) and (c) only
(D) None of the above