Final answer:
Non-homologous end joining is a DNA repair process that fixes double-strand breaks without needing a homologous sequence, potentially resulting in the deletion of a small number of nucleotides at the repair site. The correct option is B.
Step-by-step explanation:
Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. Environmental factors such as ionizing radiation or replication errors can cause these breaks. NHEJ repairs these breaks by trimming damaged DNA and joining the 'cut' ends without the need for a homologous template.
This process may result in the loss of a few nucleotides at the breakage site. Key proteins like Ku bind to the ends and prepare them for repair, which involves cleaning up the ends to make them compatible for joining. Then, DNA ligase seals the blunt or slightly overlapping ends, thus restoring the continuity of the DNA molecule.
Option B correctly defines NHEJ: "Non-homologous end joining is the repair of double-strand breaks by aligning and ligating broken ends without the need for homologous sequences." Unlike homologous recombination which repairs DNA using a homologous sequence as a template, NHEJ does not require a similar sequence and therefore results in a quicker but sometimes less accurate repair.