Rule reminder
The si impersonale (impersonal si) is used to express a general, unspecified subject — equivalent to English 'one', 'you', 'they', or 'people'. The verb is always in the third person singular. When followed by an adjective or a noun, these must be in the plural masculine form: 'Si è contenti' (not 'contento').
Quale è corretto per 'People say that the economy is improving'?