true or false and why is false?

True/False Briefly justify each answer: (a) The class of undecidable languages is closed under complementation. (b) If a language is undecidable then it is unrecognizable. (c) If a language A is regular and B mapping-reduces to A then B is also regular. (d) Suppose A is decidable. If A mapping-reduces to B and B mapping-reduces to A then B is decidable. (e) Every language mapping-reduces to its complement. (f) For languages L, L2, L3 if L mapping-reduces to L2 and L2 mapping-reduces to L3, then L mapping-reduces to L3. (8) For languages A, B if A mapping-reduces to B then B mapping-reduces to A. (h) For languages A, B if A mapping-reduces to B and B is Turing co-recognizable then A is Turing co-recognizable