Final answer:
Clustal-W is an example of iterative alignment, a process involving the refinement of multiple sequence alignments. Unlike BLAST, which focuses on rapid local alignments, Clustal-W iteratively builds and refines the alignment as sequences are added.
Step-by-step explanation:
An example of iterative alignment is B. Clustal-W. Iterative alignment is a process where multiple sequences are aligned, and based on that alignment, the original sequences might be realigned to provide an improved alignment. Tools like Clustal-W perform this type of alignment by building up a multiple sequence alignment progressively, refining the alignment as new sequences are added.
When considering the Basic Local Sequence Alignment Tool (BLAST), it is important to note that BLAST does not perform iterative alignment; rather, it is famous for its ability to rapidly align sequences by breaking down the sequence of interest into smaller segments called words and then extending these alignments to find the highest overall score. This method prioritizes speed and identifies local regions of similarity rather than comprehensively aligning sequences iteratively.