TOEFL Listening: TPO-TOEFL听力TPO - SM1272JL28W167B_R$

What is one reason for the increase in shrub growth in Arctic Alaska? A. Decreases in grass and most growth have altered the balance of nutrients in the soil. B. Increases in ground temperature have led to increased microbial activity. C. Increases in average winter temperatures have permafrost permeable to water. D. Increases in snowfall have provided more water for shrubs.