Answer:
a.Over time, a caterpillar species becomes as green as the leaves it eats.
Explanation:
<em>Evolution means the gradual formation of complex organisms from simple types, a process that usually take several years (geological time).</em>
The gradual change happens as a result of continuous adaptation by organisms to ever changing environment.
Option b could have been considered along with option a, but evolution process takes much more than 50 years.
Hence, the correct option is a.
