A synthetic strategy for converting trans -2-butene into pure cis -2-butene would consist of which of the following?

		Reaction with H 2 , Ni 2 B (P-2)
		Reaction with i) Br 2 , CCl 4 ; ii) 2 NaNH 2 , NH 3 (l); iii) Na, NH 3 (l)
		Reaction with H 3 O + , heat
		Reaction with i) Br 2 , CCl 4 ; ii) 2 NaNH 2 , NH 3 (l); iii) H 2 , Ni 2 B (P-2)
		None of these will successfully effect the desired transformation