[单选题]
The grand unified theoakcp*znnqw 0 yj5kk0 n(o-.f)ry (GUT) is a sought-after model tf:w80g+6 pwgrm 7*v epxiep*pzz95u ghat would unify three of the four forces of nature. Which force is the one it woulr76 i wpemgf xvge p5z+ 8p*:g9uw0z*pd not include?
A. gravitational
B. strong
C. weak
D. electromagnetic
