A time?sharing interest can only be a lease

________ is high in an industry when alternative products that offer attractive savings are available

A) The power of suppliers B) The threat of substitutes C) Network effects D) The switching cost

Suppose that a regression relationship is given by Y = ?0 + ?1X1 + ?2X2 + ?. If the simple linear regression of Y on X1 is estimated from a sample of n observations, the resulting slope estimate will generally be biased for ?1

But if the sample correlation between X1 and X2 is 0, the slope will not be biased for ?1.How does X2 affect ?1 if the sample correlation between X1 and X2 is zero?