Inside a greenhouse, different types of trees are kept at 3 different humidity levels. These are left for 3 years. One tree is left outside in normal conditions. The heights of the trees are measured once a week.

the answer is a or when it says crossing over

children tend to take more after their grandparents more than their parents. it’s the dna you received that was passed down to you somewhere in your family. maybe one of your grandparents had/has straight hair and you might have gotten it from them.