What goods and services have people traded throughout history

These ancient people utilized the bartering system to get the food, weapons, and spices they needed. Because of salt's great value, Roman soldiers bartered their services for the empire in exchange for salt. In Colonial America, the colonists used bartering to get the goods and services they needed.

the following best describes postwar era writers in their works:

many writers,authors,novelists,poets concentrated more on social art and social writing and stayed away from political writings.

the answer for 3 is b and the answer for 4 is d