What is an appropriate approach to testing for 'ARCH effects'? (a) Run a regression, collect the residuals, regress the squared residuals on their lags and conduct a hypothesis test to check whether the coefficients of the lagged squared residuals are equal to zero (b) Run a regression, collect the fitted values, regress the fitted values on their squared lags and conduct a hypothesis test to check whether the coefficients of the lagged squared fitted values are equal to zero (c) Employ White's test (d) All of the above.