List and discuss the assumptions you need for the Ordinary Least Squares (OLS) to be a Best Linear Unbiased Estimator (BLUE). Derive the OLS estimator, discussing where the assumptions are needed for the derivation.

Consider the following model: y = XB + , known as the Classical Linear Regression Model (CLRM), where y is the dependent variable, X is the set of independent variables, B is the vector of parameters to be estimated and is the error term