R has to be alone. If the four boys are assigned to lockers 2-5, then R must be assigned to locker 1.
Therefore, locker 1 can’t be shared.
The two shared lockers can’t be beside each other, because N and T are in the shared lockers. J shares locker 5 with one of N or T.
So locker 4 can’t be shared, because it is beside J and N/T.
D is CORRECT.
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