Which of the following terrestrial biomes is mostly made up of

Correct answer: B) Boreal forest.
The boreal forest, also known as the taiga, is a terrestrial biome characterized by coniferous evergreen trees that are adapted to cold winters and short growing seasons. It is found in subarctic regions, including northern Europe, Russia, and North America. The dominant tree species in the boreal forest are conifers such as spruce, fir, and pine, which are well-suited to the harsh, cold conditions of this biome.

The other options are not correct because:
A) Tundra is a biome characterized by low-growing vegetation, such as mosses, lichens, and low shrubs, and is found in Arctic regions.
C) Woodland/shrubland is a biome characterized by a mix of trees and shrubs, and is found in a variety of regions, but not typically in the subarctic.
D) Temperate seasonal forest is a biome characterized by deciduous trees that lose their leaves seasonally, and is found in temperate regions with mild winters and warm summers.