Which of the following could be said about ecological footprints?
a. exact ecological footprints are often difficult to calculate, but estimates can be useful in comparing populations.
b. ecological footprints can't be used to determine carrying capacity.
c. ecological footprints don't take into account resources needed to absorb and manage wastes.
d. the average ecological footprints for various countries are nearly identical.

A. Exact ecological footprints are often difficult to calculate, but estimates can be useful in comparing populations.

Which of the following could be said about ecological footprints?  Exact ecological footprints are often difficult to calculate, but estimates can be useful in comparing populations.

NOT:
b. Ecological footprints can't be used to determine carrying capacity.
C. Ecological footprints don't take into account resources needed to absorb and manage wastes.
D. The average ecological footprints for various countries are nearly identical.

They can measure  the amount of energy gained or lost