Which phenol in each of the following pairs is more acidic? Justify your choice.
(a) 2,4,6-Trimethylphenol or 2,4,6-trinitrophenol
(b) 2,6-Dichlorophenol or 3,5-dichlorophenol
(c) 3-Nitrophenol or 4-nitrophenol
(d) Phenol or 4-cyanophenol
(e) 2,5-Dinitrophenol or 2,6-dinitrophenol