Arrange the following events related to the European Union in chronological order.

(A) Greece joined the European Community
(B) Spain joined the European Community
(C) Austria has joined the European Union
(D) The Treaty of Maastricht was signed

Choose the correct answer from the options given below:

(A), (B), (D), (C)

The correct answer is Option (1) → (A), (B), (D), (C)

(A) Greece joined the European Community. 1981 January
(B) Spain joined the European Community: 1986
(D) The Treaty of Maastricht was signed. 1992
(C) Austria has joined the European Union: 1995