Correct answer is (c) Provide more permissive matching by allowing more flexible matching of residues of similar biochemical properties
To explain I would say: In this type of matching, there has to be a strict match of sequence patterns. This way of searching has a good chance of missing truly relevant motifs that have slight variations, thus generating false-negative results. As new sequences of motif are being accumulated, the rigid regular expression tends to become obsolete if not updated regularly to reflect the changes.
