How does freshwater enter the aquifer ?

According to this food web which of the following would be considered primary consumers

Pentane with molecular formula c5h12, exists in three isomeric forms. one shows linear carbon chains, another has one -ch3 groups present on the third carbon atom, and the third has two -ch3 groups present on the second carbon atom. what types of isomers are these? a. geometric isomers b. structural isomers c. halotropic isomers

Is a measure of the different types of organisms in a community. question options: tertiary secondary primary none of the above