Which one of the following characteristics is not used to classify angiosperms?
a. color of leaves
b. length of life
c. type of stems
d. number of seed leaves

a. Color of leaves

If the question goes like this: Which best describes plant classification? 
A.      Nonvascular plants are grouped into seedless and seeded plants. 
B.       Seedless plants are grouped into gymnosperms and angiosperms. 
C.      Gymnosperms are grouped into monocots and dicots. 
D.       Angiosperms are grouped into monocots and dicots.   

The best answer will be letter D. Angiosperms are grouped into monocots and dicots.     Botanists grouped or classified together according to its characteristics. 

Solution:

Support and storage of minerals these are the two functions of the skeleton depend on the dynamic nature of bone.

Thus this is the required answer.