A is correct
for B you should simply use the principles of independent events and treat it as an "or" so if the batteries are labeled as A and B the you want
P(A is rejected, OR B is rejected)
for C determine the z-scores of the quartiles adn use those to determine the z-score of the lower quartile, now take the interquartile range (in terms of z-scores) and subtract 1.5 times the IQR from the lower quartile value. you will have a z-score for the rejction value and you can read the probability from there.