Arrange the following groups of compounds in order of decreasing reactivity toward electrophilic aromatic substitution:
a. Benzene, ethylbenzene, chlorobenzene, nitrobenzene, anisole
b. 1-chloro-2,4-dinitrobenzene, 2,4-dinitrophenol, 2,4-dinitrotoluene
c. Toluene, p-cresol, benzene, p-xylene
d. Benzene, benzoic acid, phenol, propylbenzene
e. p-nitrotoluene, 2-chloro-4-nitrotoluene, 2,4-dinitrotoluene, p-chlorotoluene
f. Bromobenzene, chlorobenzene, fluorobenzene, iodobenzene