please prove the statements, show your work and explain

3. Prove whether each of the following statements about Turing reducibility are necessarily true, sometimes true, or never true. (a) For a decidable language L and an arbitrary language L2, L1 ST L2 (b) For an undecidable language L and an arbitrary language L2, Li Srl (c) If L1 ST Lfor some languages L and L2, then L, is decidable