In economics, all goods and services available to consumers are provided by
which of the following?

In economics, all goods and services available to consumers are provided by "producers".

Explanation:

A manufacturer is one who produces products or services and delivers them. Producers integrate labor and capital— the so-called factor inputs— to produce something else — that is, to production.

Business companies are the key producers' sources and are generally what economists think when thinking about production. Farmers, suppliers and building firms are instances of the producers. They also have work opportunities for people who produce the goods or provide the facilities. Manufacturers comprise corporations, government, entities and others.

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation:

during the ming dynasty