Final answer:
In the tundra biome, plants are unable to grow for much of the year , which keeps the soil frozen and hinders root growth (option a).
Step-by-step explanation:
Plants are unable to grow in the tundra biome because the soil is frozen most of the year. This condition is due to the presence of frost, a layer of soil that remains perpetually frozen and makes it extremely difficult for plant roots to penetrate deeply. The Arctic tundra, in particular, experiences such severe conditions, with low temperatures, short growing seasons, poor nutrients, and little precipitation.
However, during the brief summer, when the frost thaws slightly at the surface, a burst of productivity occurs and the ground can be completely covered with plants or lichens that are low to the ground, such as low shrubs, grasses, and small flowering plants.
Hence, the answer is option a.