When homologous chromosomes crossover, what occurs?
a) two chromatids get tangled, resulting in one re-sequencing its dna.
b) two sister chromatids exchange identical pieces of dna.
c) specific proteins break the two strands and re-join them with their homologs.
d) each of the four dna strands of a tetrad is broken and the pieces are mixed.
e) maternal alleles are "corrected" to be like paternal alleles and vice versa.

The image shows a sandstone formation with visible bands of different colors. what do the bands indicate about how this sedimentary rock was formed? choose two answers. a). the rock was made from more than one material. b). water was absent during the compaction and cementation process. c). sediments and other matter were deposited in layers before lithification. d). the rock was stretched horizontally by the pressure from surrounding rocks. e). layers of hot liquid in the rocks cooled and solidified at different tempatures