Final answer:
The largest native upland game bird in Alberta is the Sage Grouse, known for its distinct mating displays and larger size compared to other upland game birds in the region.
Step-by-step explanation:
The largest native upland game bird found in Alberta is B. Sage Grouse. They are well-known for their unique mating displays on leks, which are communal breeding grounds. Compared to other birds on the list, such as pheasants, sharp-tailed grouse, and Hungarian partridges, the Sage Grouse is significantly larger, which helps differentiate it in size among Alberta's native upland game birds.