Final answer:
The black spruce is the dominant species in the boreal forest.
Step-by-step explanation:
In the boreal forest, the species that dominates is the black spruce (option B).
The long and cold winters in the boreal forest have led to the predominance of cold-tolerant cone-bearing plants. These are evergreen coniferous trees like pines, spruce, and fir, which retain their needle-shaped leaves year-round. Evergreen trees can photosynthesize earlier in the spring than deciduous trees because less energy from the Sun is required to warm a needle-like leaf than a broad leaf. The black spruce is one of the dominant evergreen coniferous species in the boreal forest.