Which of the following is the best definition of a chromosome?
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a. a section of dna that codes for traits
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b. a combination of dna and proteins in the nucleus of a cell
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c. the pigment that gathers light for photosynthesis
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d. the main site of photosynthesis in plant cells

Even though the ostrich is a flightless bird, ostriches still possess wings that stretch approximately two meters across when fully extended. scientists speculate that when dinosaurs became extinct, some of the birds that lived during that time became land dwellers since they were able to consume the food that the dinosaurs once ate. over time, these species grew larger and heavier. eventually, the ostrich species became too big to fly. the wings found on ostriches are known as a. analogous structures. b. homologous structures. c. vestigial structures. d. symmetrical structures.