Correct Option: A

BLAST (Basic Local Alignment Search Tool) is a program which is used for local similarity search. BLAST is an algorithm for comparing primary biological sequence information, such as the amino-acid sequences of different proteins or the nucleotides of DNA sequences. A BLAST search enables a researcher to compare a query sequence with a library or database of sequences, and identify library sequences that resemble the query sequence above a certain threshold. Different types of BLASTs are available according to the query sequences like nBLAST (nucleotide BLAST), pBLAST (protein BLAST) etc.