Tamara has a hard time remembering pin numbers for her credit cards, but she wants to keep the information secure. which is the best solution for her dilemma?

Carry a pen on you and right on your hanf or a pice of paaper or use apps in your phone to write down things

The best solution for her dilemma might be writing the pin numbers down in one list and keeping them in a safe place at home. This is the most secure method to not get stolen because it would be only just one list with no chances to get copied and she would be the only one in knowing where it is. Keeping them on her smartphone does not seem like a good idea because it can get hacked, or stolen, or accidentally copy it and send it by mistake to someone, so to avoid this kind of problem, the old fashion written list is the best option.

this null effect is caused by a weak manipulation and ineffective internal validity. in a scientific study, as the one dr. morimoto is trying to perfom, internal validity refers to the confidence placed in the cause-effect relationship and to how well an experiment is done and able to eliminate confounding variables.