Choose the incorrect statement below: One of the main costs of the single-index model is that it imposes some restrictions on the asset return structure. Therefore, The covariance estimates are simpler and more precise. The variance estimates are generally lower in the Markowitz procedures. The covariance estimates are simpler but less precise. The single-index model helps with specialization in security analysis. Suppose we want to estimate the beta of Apple based on the index model. The estimated number is 3 . What does it mean? When the market return increases by 1%. Apple's return increases by 3% on average. The correlation between the market return and Apple's return is 3%. The variation in the market retun can explain 3% the variation in Apple's return. When the market return increases by 1%, Apple's return increases by 4% on average