问题如下：
An economic forecasting firm has estimated the following equation from historical data based on the neoclassical growth model:
Potential output growth = 1.5 + 0.72 × Growth of labor + 0.28 × Growth of capital
The intercept (1.5) in this equation is best interpreted as:
选项：
A. the long-run sustainable growth rate.
B. the growth rate of total factor productivity.
C. above trend historical growth that is unlikely to be sustained.
解释：
B is correct.
The estimated equation is the standard Solow growth accounting equation. The intercept is the growth rate of total factor productivity.
考点：TFP
解析：本题直接考察TFP的表达形式，它的增长在公式中表示为方程的截距项。
请问A选项怎么理解？
