Sequence alignment tools are software programs used to align biological sequences (DNA, RNA, or protein) to identify regions of similarity.
Let's analyze the options:
(a) BLAST (Basic Local Alignment Search Tool): A very widely used heuristic algorithm and program suite for finding regions of local similarity between sequences. It compares a query sequence against a database. It IS a sequence alignment tool.
(b) FASTA: Another popular heuristic algorithm and program suite for sequence database searching and local sequence alignment. It was developed before BLAST but uses similar principles. It IS a sequence alignment tool.
(c) CLUSTAL (e.g., ClustalW, Clustal Omega): A widely used program for performing multiple sequence alignment (aligning three or more sequences). It IS a sequence alignment tool (specifically for multiple sequences).
(d) ROSMAL: This term does not correspond to a well-known or standard sequence alignment tool in bioinformatics. There might be very specialized or obscure tools with similar names, but in the context of common bioinformatics tools, BLAST, FASTA, and CLUSTAL are standard.
Therefore, ROSMAL is the one that is likely "not a sequence alignment tool" among the common, widely recognized options.
\[ \boxed{\text{ROSMAL}} \]