Correct Answer - Option 4 : T
From statement: Q has third highest weight weighing 88 kgs.
_ > _ > Q(88) > _ > _ > _ > _
From statement: Three people have weights valuing between Q and P.
_ > _ > Q(88) > _ > _ > _ > P
From statement: No one is weighing between P and S and the second lowest weighs 78 kgs.
_ > _ > Q(88) > _ > _ > S(78) > P
From statement: R is immediately before S in weight, T is immediately before U in weight.
⇒ T > U > Q(88) > _ > R > S(78) > P
⇒ T > U > Q(88) > S > R > S(78) > P
∴ T has the highest weight among them.