Thanks a ton for this the clear explanation. That was very helpful. And yes, as you said the following code works.
Code: Select all
\documentclass[12pt,monochrome]{article}
\usepackage{tikz}
\usepackage{xcolor}
Perhaps, earlier when I tried adding the monochrome option to the \documentclass, I forgot to remove it from xcolor. Anyway, as you have suggested I will remove the redundant \usepackage{xcolor} command.
Also, your suggestion worked for the case of two packages where I was having a conflict. That's great. Juanjo, thanks so much for all your help.
Gmedina, thanks to you too for your suggestion.