Abook review would be considered
a. a primary source.
b. a secondary source.
c. a tertiary source.
d. either a secondary or tertiary source, depending on content.

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes