Which is occurring during conjugation? A. There is a change in the nucleotide sequence of a DNA molecule.

B. A bridge-like connection is created between bacterial cells for genetic material to
be transferred.

C. A bacterial cell takes DNA fragments from a dead cell and incorporates them into
their DNA molecule.

D. There is a transfer of DNA from bacterium to another by a virus.

B. A bridge-like connection is created between bacterial cells for genetic material to  be transferred.

Explanation:

A. There is a change in the nucleotide sequence of a DNA molecule.  - this is describing a genetic mutation

B. A bridge-like connection is created between bacterial cells for genetic material to  be transferred.  - this is conjugation, a type of genetic transfer between donor and recipient bacterial cells. It is a way that bacterial cells achieve genetic variation. For example, bacteria can share antibiotic resistance genes between one another. They do not directly contact one another, instead, they use a structure called a pilus to exchange material

C. A bacterial cell takes DNA fragments from a dead cell and incorporates them into  their DNA molecule.  - this is transformation, another type of genetic transfer where bacterial cells take up bacterial DNA from the environment. These molecules of DNA are usually from dead bacteria

D. There is a transfer of DNA from bacterium to another by a virus. - this is another type of gene transfer called transduction, where a virus takes genetic material from one bacteria to another.

the backbone of the dna and rna compound is sugar phosphate.