A common market refers to $\_\_\_\_\_\_\_\_.$

a group of countries committed to $(1)$ removing all barriers to the free flow of goods and services between each other and $(2)$ the pursuit of a common external trade policy

a group of countries committed to $(1)$ removing all barriers to the free flow of goods, services and factors of production between each other and the $(2)$ pursuit of a common external trade policy

a group of countries committed to $(1)$ removing all barriers to the free flow of goods and services between each other but pursuing independent external trade policies

a group of countries committed to $(1)$ removing all barriers to the free flow of goods, services and factors of production between each other; $(2)$ the adoption of a common currency; $(3)$ the harmonization of tax rates; and the $(4)$ pursuit of a common external trade policy