Viruses can enter the body through various routes, but commonly they enter through the intestinal tract (such as through contaminated food or water) or through the respiratory tract (by inhaling respiratory droplets). Once inside, they can spread through the bloodstream to other parts of the body.
In this context, the options you listed suggest that a virus can enter the body through the intestinal tract or by infecting a cell directly, and then it can spread via the bloodstream.
So the best answer would typically be intestinal tract if we're thinking about initial entry points for many viruses.