[单选题]
The grand unified theo2, xcdvs av. j82wy.uery (GUT) is a soughdbx38b)hkr frca961yoqn e 96t-after model that would unify three of thec rhd3bknab)91orqf 6x9 y6 8e four forces of nature. Which force is the one it would not include?
A. gravitational
B. strong
C. weak
D. electromagnetic
