A!!!!
Because is the one that screams less!!!!

"I just need help supporting my choice"

Unfortunately, stating "some people on the internet liked X" probably isn't going to win over the stakeholders.

In general, designers want it smaller, marketing wants it bigger. Given the very limited amount of info, I'd say if the cover, overall, emphasizes the visual brand, go smaller. If it's generic and the logo is the only thing to identify the company, bigger might be the only option.

I understand the desire to maintain your client's privacy, but you can't judge the best size for a logo by looking a generic placeholder. Logos vary considerably in their proportions, boldness, etc.

But as a general comment, it's usually not a good idea to put a logo over a patterned background, like in layouts C and D. In fact most corporate identity manuals specifically prohibit it.

Marketing and sales just never understand why less is more. I don't have much fight left in me these days.