Which section from the article BEST explains why Dorothea Lange practiced documentary photography?

Seed plants that lived during the carboniferous impact life on earth today because a. they are the ancestors of all plant life on earth. b. their remains formed coal, which is an important resource. c. they produced fossils that are used to date many geologic events. d. their presence caused oxygen levels to drop, allowing animals to evolve.

Mention any one function of transparency international?

Given: circle a externally tangent to circle b. how many possible common tangents to circles a and b can exist? 2 3 4