With a partial trade agreement A) goods and services are allowed to cross boundaries without tariffs.
B) two or more countries agree to liberalize trade in a selected group of categories.
C) two or more countries set common tariffs toward non-members.
D) two or more countries allow the free mobility of inputs such as labor and capital.
E) two or more countries agree on establishing a common currency.

B) two or more countries agree to liberalize trade in a selected group of categories

Explanation:

A partial trade agreement occurs when trade liberalisation occurs in respect of some of the restrictions placed on some commodities or categories.

Trade liberalisation occurs when countries that are trading with one another decide to reduce or remove restrictions that will affect free exchange between the nation.

Such restrictions include tariff, licencing and quotas.