America's nuclear arsenal has expanded, but China's and Pakistan's too.

A- but China's and Pakistan's too.
B- and also China's and Pakistan's.
C- but so have China's and Pakistan's.
D- and so also China's and Pakistan's .
E- but so did China's and Pakistan's .

my doubt: i find this question faulty. the proclaimed answer is C . but what is bothering me is that how can this SC use "BUT" when the intention is not of contrast but of "similar idea"