What Is the Primary Difference Between Revenues and Gains

What is the primary difference between revenues and gains?

A) Gains are increases in net assets from peripheral activities while revenues are increases from ongoing central activities.
B) International financial reporting standards makes no distinction between them since they both increase income.
C) Revenues cause increases in net assets as a result of peripheral activities and gains cause increases through ongoing central activities.
D) Both revenues and gains cause a decrease in net assets from ongoing central and peripheral transactions respectively.