x,y,z∈R, find the minimal value of f(x,y,z)=2x2+5y2+10z2−2xy−4yz−6zx+3.<spanclass=′latex−bold′>(A)</span>0<spanclass=′latex−bold′>(B)</span>3<spanclass=′latex−bold′>(C)</span>−3<spanclass=′latex−bold′>(D)</span>1<spanclass=′latex−bold′>(E)</span>None