The correct answer is C. The permafrost ground prevents deep root growth
Step-by-step explanation:
Tundra is a biome characterized by cold temperatures, low vegetations (grasses, shrubs, mosses), and a subsoil covered by permafrost, which refers to a subsoil that has a temperature lower than 0° C and may contain ice. This permafrost is responsible for the presence of low vegetation and the lack of high vegetation such as trees, this can be explained as the low temperature along with possible ice prevents deep root growth and this stops trees and similar plants from obtaining nutrients and therefore thrive. According to this, the reason tundra lack trees is that the permafrost ground prevents deep root growth.