tangent = opposite / adjacent
In the diagram:
TQ is the short leg or the opposite
QR is the long leg or the adjacent
TR is the hypotenuse. TS is part of the hypotenuse.
Tan(QTR) = TQ / QR
TS = 1 ; TQ = TS so, TQ = 1
Tan(QTR) = 1/QR
I think the answer is C.RQ