Please help quick due soon! The material in the outer core is a fluid. A fluid is any material that can flow, such as a liquid or gas. Within a fluid, differences in density can cause motion. The parts of the fluid that are denser sink to the bottom. The parts of the fluid that are less dense float to the top. Thus, differences in density cause convection in water being heated on a stove,

During crossing-over, a. genetic material is exchanged between nonsister chromatids, resulting in new combinations of alleles. b. nonsister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. c. one homologous chromosome of a tetrad is exchanged with another tetrad, resulting in new combinations of alleles. d. sister chromatids from each homologous chromosome of a tetrad are exchanged, resulting in new combinations of alleles. e. genetic material is exchanged between sister chromatids, resulting in new combinations of alleles.