For product A, standard cost for 790kgs is $6.15 per kg and the actual cost incurred for 850kgs is $6.90 per kg. Calculate the materials price variance. (Round the intermediate calculations to two decimal places and the final answer to the nearest whole dollar). Choose an answer a. Materials price variance is $638 Unfavorable. b. Materials price variance is $738 Favorable. c. Materials price variance is $988 Favorable. d. Materials price variance is $618 Unfavorable. Show your process step by step