I use both methods, depending on the rack I am building and my mood at the time 
Option B can become more useful when you are using a single reverb plugin for multiple plugins (like as a send effect). If using option B you should make sure the reverb is at 100% wet and then you control the mix using the GP audio mixer you have next in the chain.
The Reverberate manual mentions the ‘Settings’ tab where you can over ride the default preset wet/dry mix and set them all to 100% wet if you are using it as a send effect.
This topic has some screenshots and explanations of more complex routings that I found useful.