Apsychologist is interested in looking at the effectiveness of a new computer program in students learn math. she decides to test this new program with a group of middle school students. at this particular school, the boys and girls tend to be disruptive when they are in the same classroom, so she decides to run them separately in the experiment. she creates a group of boys who use the computer program four times per week. she creates a group of girls who do not use the computer program to serve as a comparison group. this experimental design is flawed because gender is a and as a result, the internal validity of the study has been

Three thieves agreed to rob a bank. the first was to steal a car to be used for the getaway, the second agreed to procure weapons, and the third would check the bank for cameras. the car thief stole a car and parked it in a lot behind his girlfriend's apartment building. while visiting her the night before the robbery, the car thief suffered a series of convulsive seizures. he was rushed to the hospital where he was placed in the intensive care unit and heavily sedated. meanwhile the two other thieves, unaware of their accomplice's illness, met and decided to rob the bank on their own, despite the absence of a getaway car and driver. they robbed the bank, but were quickly apprehended as they tried to escape and implicated the car thief under police questioning.the car thief can be charged with: a theft of the car only.b conspiracy to commit robbery and theft of the car only.c robbery and theft of the car only.d theft of the car, conspiracy to commit robbery, and robbery.