Is Rebecca’s conclusion valid or not valid?

Chantel used How To Evaluate an Experiment Conclusion to help decide. She assumed that the experiment was a fair test because she was told that it was. Then she determined that the reason Rebecca used to support her conclusion was poor because her reason was an opinion. Even though Rebecca’s conclusion was a correct statement, her supporting reason was poor. Chantel decided that Rebecca’s conclusion was not valid. (Scientists place high value on providing good supporting reasons.)