If you start with 100g of carbon 14, how much will remain after 4 half lives?

"a.) well–developed vascular system."

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

the question isn't complete here so i can't right an answer '_'

the most common type of reef is the fringing reef. this type of reef grows seaward directly from the shore. they form borders along the shoreline and surrounding islands.