Why does Mariam say yes to marry Rasheed?

Mariam protests the marriage contract and ends up locked in her room as a result. At the ceremony she refuses to speak and numerous throats are cleared around the room. Jalil then shows Mariam her face in a mirror, which she scrutinizes..... then she sees Rasheed's face for the first time. Without explanation.... and after much scrutiny, she says "yes" as she is prompted.