$A$ point moves in the $x-y$ plane according to $x = kt$ and $y = kt(1 - \alpha t)$,where $k$ and $\alpha$ are positive constants. The equation of the trajectory is:

• A
  $y = x - \frac{\alpha x^2}{k}$
• B
  $y = x + \frac{\alpha x^2}{k}$
• C
  $x = y - \frac{\alpha y^2}{k}$
• D
  $x = y + \frac{\alpha y^2}{k}$