单项选择题
The relationship between the chained speed of development and the fixed base speed of development is ( ).
A.Chained speed of development = fixed base speed of development
B. The product of the chained speed of development is equal to the fixed base speed of development
C. The sum of the chained speed of development is equal to the fixed base speed of development
D. The difference of the chained speed of development is equal to the fixed base speed of development