Bella leaves her office building only to find it is raining. She returns to her office and gets a trash bag out of the supply cabinet. Using a pair of scissors, she cuts the bag so that she can put her head and arms through the bag without getting wet. In using the trash bag as a makeshift rain jacket, Bella has overcome:.
1. confirmation fixedness.
2. creativity bias.
3. confirmation bias.
4. functional fixedness.

Functional fixedness

Explanation:

Functional fixedness: It is a type of cognitive bias that leads people toward using the object only in the traditional way. It does not allow the brain to explore or grow and people stop innovating new ideas. It has a lot of impact on our life and career to grow. To overcome this situation, people need to take a break and try to visualize the issue, so he can handle it and let the problem go away.  

In the given case, Bella uses a trash bag as a makeshift rain jacket, Bella has overcome functional fixedness.

(75years ,i believe is the correct answer.good luck