As U and V each grow only in medium 1 and none other. T and Z each grow in medium 2 and in medium 3. But not in medium 1. Thus X can be isolated and identified as it grows in medium 3 only. Y can then be identified as it grows only in medium 2. W does not grow in medium 2. Only medium 1 and medium 3 are suitable for this bacteria. Thus W, X and Y can be identified.
If U and W are identified, it leaves T and Z. If X and T are identified, then U and V remain unidentified. Since U and V can grow only in the same medium as also the pair T and Z. The only additional information to accurately identify all seven types of bacteria would be possible with additional information that allows for identification of V and Z.
Following on the premise if X is Frank’s group, Z will be Gloria’s group. Also T and Z cannot be in the same group i.e. in Gloria’s group. Hence any of the following could be in Gloria’s group except T.
When V is in Frank’s group it cannot be in Gloria’s group as per the restriction that no print can be in both groups. When W belong to Frank’s group, then U will belong only to Gloria’s group and when X is Frank’s group Z must necessarily be in Gloria’s group. Also since W and Y cannot be in the same group, A is ruled out. B is ruled out as T and Z cannot be in the same group. C is ruled out because X and Z cannot be in the same group as also in the case of E, where Frank’s group WYZ does not conform to the restriction that W and Y cannot belong to the same group.
Since U is in Frank’s group, W must be Gloria’s group. But W and Y cannot be in the same group. Therefore Y cannot be in Gloria’s group.
Since U and X are in Frank’s group, it necessarily follows that W and Z belong to Gloria’s group. Thus A has only W and not Z and B & D only Z and not W, they are incorrect that leaves C and E. Now W and Y cannot belong to the same group. Therefore Gloria’s group must consist of V, W & Z, if U and X are in Frank’s group.
Since the premise is a logical fallacy, the inference B which is also a logical fallacy is true. Rest of the inferences are logical conclusions. Hence the answer is B.