premise: Shout Across the River is a stage play, written by Stephen Poliakoff, which premiered at the RSC Donmar Warehouse (at that time called The Warehouse) in London in September 1978. It was directed by Bill Alexander. It featured Gwyneth Strong in the lead role of a troubled eighteen-year-old girl. The cast also included Lynn Farleigh, David Threlfall, Nigel Terry and Andrew Paul.
hypothesis: The youngest character in Shout Across the River is 18 years old.
reason: Based on the context, there isn't a way to know whether the youngest character is 18 years old. It only states that the lead characters is 18. I think it's difficult for the AI, because the AI doesn't have enough information to understand if this may or may not be true.