Which two important things do many economics systems not considered to have value?

a. natural resources and human labor
b. supply and demand
c. capital and consumption
d. good and services

i was thinking a

Option A , natural resources and human labor

Explanation:

These days there is heated conversation everywhere regarding the sustainable development but when it comes to accountability of naturally available resources, most of the nations do not have any indices to measure the  consumption rate of natural resources or the left out resources.

Human population however is not even considered a resource in most of the nation and thus its accountability is questionable in all the nations.  

Hence, option A is correct