During the early stages of meiosis, two chromosomes in a homologous pair may exchange segments, producing genetic variation in sex cells. this process of exchange is called a) transcription. b) crossing over. c) nondisjunction. d) genetic shuffling.

The correct answer is option B, that is, crossing over.  

Crossing over or chromosomal crossover refers to the interchange of genetic substance between the two homologous chromosomes non-sister chromatids, which leads to the formation of recombinant chromosomes at the time of sexual reproduction.  

It takes place in the pachytene stage of prophase I of meiosis at the time of a procedure known as synapsis.  

there are mainly three domains in biological classification namely; archaea, bacteria, and eukarya.

archaea includes all the prokaryotic cells which are characterized by their lipid membranes. they have branched hydrocarbon which is attached to glycerol through an ether linkage.

bacteria includes all the prokaryotic cells, the cell membrane of which are made up of the unbranched fatty acid chain. in addition, they are attached to glycerol through an ester bond.

eukarya includes all the eukaryotic cells, that is, the cells contain a nucleus and other membrane-bound cell organelles.

they can be autotrophic as well as heterotrophic, unicellular as well as multicellular

they include kingdoms like protista, plantae, animalia, fungi et cetera.

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explanation:

i'm thinking (a) to keep sand in place; ////////////

explanation: a sand fence or sandbreak, like a snow fence, is used to force windblown, drifting sand to accumulate in a desired place. sand fences are employed to control erosion, sand dune stabilization, keep sand off roadways, and to recruit new material in desert areas.