Which best describes chromosomal deletion?
occurs when part of a chromosome breaks off and is inserted into the middle of another chromosome
occurs when part of a chromosome breaks off and reattaches backward on the same chromosome
occurs when part of a chromosome breaks off and does not reattach
occurs when part of a chromosome breaks off and attaches to another chromosome

Chromosomal deletion is the loss of genetic code, caused by a segment of chromosome breaking away during DNA replication. The best answer is the third one, "when part of a chromosome breaks off and does not reattach."

The first answer, "part of a chromosome breaks off and is inserted into the middle of another", describes chromosomal insertion.

The second answer, "part of a chromosome breaks off and reattaches backward", describes chromosomal mutation.

The final answer, "part of a chromosome breaks off and attaches to another", describes chromosomal translocation.

Your answer is b. codominant