Different kinds of mycorrhizae occur in different ecosystems. For example, as you walk up a mountain, you might find one type of mycorrhizae in lower regions and a second, different type of mycorrhizae in higher regions. Why are there mycorrhizae specific to certain ecosystems?
A. Mycorrhizae tend to colonize all levels of the mountain.
B. Mycorrhizae are adapted to the type of soil and the type of vegetation present.
C. Mycorrhizae are adapted to the altitude.
D. Mycorrhizae are adapted to the type of slope of the land.

Option B, Mycorrhizae are adapted to the type of soil and the type of vegetation present.

Explanation:

Mycorrhiza is a kind of mutualistic association between the terrestrial plants and fungi which is essential for the retrieval of critical elements from the organic compound and also protect  the terrestrial plant from pathogenic fungi.

It has metalliferous nature and hence is affected by the soils and its geographical isolation, abiotic components such as mineral type, climate etc.  

Due to this reason Different kinds of mycorrhizae occur in different ecosystems

Hence, option B is correct

the denominator has a very specific role.