Final answer:
Among the options, (CH3)3CO- or tert-butoxide ion is the reagent that will favor an E2 reaction with all substrates because it is a bulky, strong base that is less nucleophilic and promotes the E2 elimination pathway over the SN2 substitution pathway.
Step-by-step explanation:
The student is asking which reagent will favor an E2 reaction with all substrates. The E2 reaction is a bimolecular elimination reaction where a proton is removed from the substrate, and a double bond is formed, usually in the presence of a strong base. Among the given options, (CH3)3CO-, or a tert-butoxide ion, is the reagent that will favor an E2 reaction with all substrates. Tert-butoxide is a bulky, strong base that is less nucleophilic due to its size and is therefore more likely to abstract a proton, leading to the elimination product rather than substitution. The steric hindrance of the tert-butoxide makes it difficult for SN2 reactions to occur, especially with sterically hindered tertiary substrates.