This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

The Social Charter was subsequently adopted in 1989 by 11 of the then 12 member states. The UK refused to sign the Social Charter and was exempt from the legislation covering Social Charter issues unless it agreed to be bound by the legislation. The UK subsequently was the only member state to veto the Social Charter being included as the "Social Chapter" of the 1992 Maastricht Treaty - instead, an Agreement on Social Policy was added as a protocol. Again, the UK was exempt from legislation arising from the protocol, unless it agreed to be bound by it. The protocol was to become known as "Social Chapter", despite not actually being a chapter of the Maastricht Treaty. To achieve aims of the Agreement on Social Policy the European Union was to "support and complement" the policies of member states. The aims of the Agreement on Social Policy are:
How many member states adopted the Social Charter in 1989?