organic chemistry - nucleophilic aromatic substitution

A nucleophilic aromatic substitution is a substitution reaction in organic chemistry in which the nucleophile displaces a good leaving group, such as a halide, on an aromatic ring. This is an unusual reaction for H2 Chemistry students because electrophilic aromatic substitution is usually encountered for arenes.

   

 An example:

    SNAr mechanism:

In the mechanism, electron withdrawing groups activate the ring towards nucleophilic attack, for example if there are nitro functional groups positioned ortho or para to the halide leaving group.

Explain which mechanism will yield the fastest rate given that the nucleophile is methoxide ion, CH3O-, and the each of the substrates are given below. Draw the organic products that are formed.