Answer:
Grows, Factor of 2
Explanation:
The relationship between the elapsed time, t, in years, since Takumi started studying his tree, and the total number of its branches, N(t), is modeled by the function:
For illustration, let us take the growth for the first three years after he started studying the number of branches.
We notice that for each subsequent year, the number of branches doubles.
Therefore:
Every year, the number of branches grows by a factor of 2.