Which amendment to the u. s. constitution protects the rights of women to vote? a. seventeenth b. twenty-sixth c. fifteenth d. nineteenth

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.        

could you show the options for the answers? : )