TASK DEFINITION: In this task, you are given a sentence and a question, you would be asked to create the answer which is contained in the sentence provided.
PROBLEM: Sentence: Leaves changing color on trees of these is the best sign that the fall season has begun. Question: Which of these is the BEST sign that the fall season has begun?

SOLUTION: Leaves changing color on trees

PROBLEM: Sentence: A(n) polyploid is an individual with more than the correct number of chromosome sets. Question: What is an individual with more than the correct number of chromosome sets called?

SOLUTION: polyploid

PROBLEM: Sentence: Most, if not all, of the extant animal phyla today evolved during the cambrian period, yet many of mass extinctions devastating events have taken place since then. Question: Most, if not all, of the extant animal phyla today evolved during the cambrian period, yet many of what devastating events have taken place since then?

SOLUTION:
mass extinctions