The equation of a line in the form \( y = mx \) describes a proportional relationship through the origin, where \( m \) is the slope of the line.
- Option A: \( y = \frac{1}{2}x \) has a slope of \( \frac{1}{2} \).
- Option B: \( y = x \) has a slope of \( 1 \).
- Option C: \( y = 2x \) has a slope of \( 2 \).
All three options describe lines through the origin and represent proportional relationships.
To summarize:
- \( y = \frac{1}{2}x \) reflects a lower proportionality to \( x \).
- \( y = x \) reflects a one-to-one proportionality to \( x \).
- \( y = 2x \) reflects a greater proportionality than \( x \).
Thus, all three equations \( y = \frac{1}{2}x \), \( y = x \), and \( y = 2x \) are valid equations for lines that describe proportional relationships through the origin.