Verbal Reasoning — Classification (odd-one-out): Choose the word that does not belong to the same category. Options: Oyster, Clam, Scallop, Mussel Use biological traits (mobility/habitat/attachment) to spot the outlier. Select the single different word.

Given data

• Oyster, Clam, Scallop, Mussel.

Concept/Approach
All four are bivalve mollusks, but their typical mode of life differs. We look for one that does not match the usual stationary/burrowing lifestyle.

Reasoning
Oyster → commonly cements to rocks/pilings (sessile).Clam → mostly burrows in sediment.Mussel → attaches by byssal threads; sedentary.Scallop → capable of swimming by clapping valves; free-moving compared with the rest.

Decision
The only free-swimming bivalve in the list is the Scallop.