Answer:
Option C, labor, is the right answer.
Explanation:
In economics, those factors used in the manufacturing process to produce goods generally finished goods and services, are known as the factors of production. The land, labor, enterprise and capital are the four basic factors of production. The producer can increase his factors of production to increase the production of goods and services.
In the given question, Niall has hired additional editors and replaced the old webmaster, therefore, he is increasing his labor to increase the production.