When the Ring-Necked Pheasant Was Introduced from China to the United

When the ring-necked pheasant was introduced from China to the United States, it increased in population, stabilized, and did not appear to cause any detrimental effects on the populations of any of the plants or animals in the regions in the Midwest where it lives. Therefore, it probably

A) filled a realized niche previously occupied by another bird.
B) filled a fundamental niche previously not occupied.
C) experienced extensive competitive exclusion.
D) experienced density-dependent limiting factors.
E) experienced extreme density-independent limiting factors.