Heres the words I would use:
a. mechanized - with machinery, in this case the sentence would mean "they have less machinery in"
b. mechanical - mechanical objects are objects that are machines. In this case, the sentences compares old machine based systems with new electromagnetic based systems.
c1. mechanism - a mechanism is something made up of working parts, such as the brain.
c2. mechanized - with machinery. In this case, its saying the brain doesn't have machenery in, where as a computer does.
I can explain this futher if you like. In some cases there is more than one plausable option, but I think i have chosen the most semantically plausable.