Option 1 states that decisions of the General Assembly are binding on all members. This is incorrect. The General Assembly is a representative body where each member state has one vote. While its decisions hold great political weight, they are not legally binding on member states.

Option 2 states that the term of the non-permanent members of the Security Council is for three years. This is incorrect. The term of non-permanent members of the Security Council is for two years. Each year, the General Assembly elects five non-permanent members to serve on the Security Council.

Option 3 states that the International Court of Justice has 20 Judges elected for a period of five years. This is incorrect. The International Court of Justice, the principal judicial organ of the United Nations, consists of 15 judges. They are elected by the General Assembly and the Security Council for a term of nine years.

Option 4 states that the Trusteeship Council has been suspended since 1 November 1994. This is correct. The Trusteeship Council was established to oversee the administration of trust territories until they attained self-government or independence. Since its main task was completed, the Trusteeship Council has been in a state of suspension since November 1994.

In conclusion, option 4 is the