Correct option is (D) 60°
Sum of angles in a quadrilateral is \(360^\circ.\)
\(\therefore\) In quadrilateral BELT,
\(\angle B+\angle E+\angle L+\angle T\) \(=360^\circ\)
\(\Rightarrow\) \(80^\circ+100^\circ+120^\circ+\angle T=360^\circ\)
\(\Rightarrow\) \(300^\circ+\angle T=360^\circ\)
\(\Rightarrow\) \(\angle T=360^\circ-300^\circ=60^\circ\)