anh chi da co su thay doi trong nhan thuc va hanh dong nhu the nao sau khi nghien cuu mon hoc chu nghia xa hoi

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.        

it should be d or b but i'm sure it's d

answer; dead end or culdesac;

answer; caravan;