What Is the Difference Between a Research Brief and a Research

What is the difference between a research brief and a research proposal?

A) There is no essential difference between the documents, although both facilitate the research process
B) A research proposal is a written document stating the proposed sampling process, whereas a research brief is a document summarizing the main finding of the research report
C) A research proposal is a written document stating the client's requirements whereas a research brief is a document defining what the marketing research agency promises to do for its client and how much it will cost
D) A research brief is a written document stating the client's requirements whereas a research proposal is a document defining what the marketing research agency promises to do for its client and how much it will cost