What are the possible problems that can arise when a simple linear regression model is used when

(a) the explanatory variable is measured with error?

(b) there is a nonlinear relationship between the response and the explanatory variable?

(c) the error term does not have mean 0?

(d) the standard deviation of the error term is not constant over the range of the explanatory variable?

(e) the error term is not approximately normally distributed?