Answer:
The correct option is B.
Explanation:
The slope intercept form of a line is

Where, m is slope and b is y-intercept.
if a line passing thorough two point then the slope of the line is

The line passing through the point (0,6) and (1,8), so the slope of the lien is

The slope of line is 2, it means the birch tree grows 2 inches per month.
From the given graph it is clear that the y-intercept of the line is 6 and the slope is 2. So, the equation of line is

Put x=10.

The height of the birch tree will be 26 inches after 10 months.
Therefore, the correct option is B.