• Correlated Response to Selection ($CR_Y$): When selection is practiced on trait $X$, the indirect response observed in an unselected trait $Y$ is given by Falconer's formula:

where $r_g$ is the genetic correlation between traits $X$ and $Y$.

• Impact of Genetic Correlation:
• When traits are positively genetically correlated ($r_g \gt 0$), selecting for higher values of trait $X$ produces a strong, concomitant positive increase in trait $Y$.
• If traits are unrelated ($r_g = 0$), the expected correlated response is zero.

Correct option: (2) Positively related traits