What Is Meant by a Multiple Regression

What is meant by a multiple regression?

A) The same variables (both independent and dependent) are simply run multiple times in the same regression to ensure statistical significance.
B) The same regression is run as was previously run, but with multiple independent variables (X) to estimate one cost function.
C) The same regression is run with the same variables, but with supporting analyses such as account analysis and high-low method.
D) The use of the same regression run multiple times to eliminate the need for the evaluation criteria for the validity of the input and output.