Relative Clauses: defining or non-defining?

1 He sold empty bottles and old newspapers. He asked the highest possible price for them. 2 We had to complete a text. Some words had been deleted from it. 3 Brenda gets the opportunity. Freda has been after it all her life. 4 Britain has a "mixed" economy. This means that part of its industry has been nationalized. 5 Authors of detective stories usually end their books with an epilogue. In this epilogue the name of the criminal is made known. 6 The author uses formal language in everyday situations. This makes his play quite funny at times. 7 Something must be done about the situation in Ulster. Ulster is divided into Catholic and Protestant ghettos. 8 Will stays with his wife because of his daughter. He loves his daughter very much.