Given a dataset D={(1,2),(10,2),(4,6),(0,4)}, where the first number in each tuple is the input xi and the second number is the label yi. Consider the regression model y^i=b (i.e.: the predicted label is always the same, but b is a model parameter and can be optimized). Suppose the loss function L(b)=i=1N(yiy^i)2. What is the optimal parameter b ? 2.5 0 1 5 None of these are correct