In the One Factor (APT)Model,the Characteristic Line to Estimate βI

In the One Factor (APT) Model,the characteristic line to estimate βi passes through the origin,unlike the estimate used in the CAPM because:

A) the relationship is between the actual return on a security and the market index.
B) the relationship measures the change in the security return over time versus the change in the market return.
C) the relationship measures the change in excess return on a security versus GNP.
D) the relationship measures the change in excess return on a security versus the change in the factor about its mean of zero.