John is a 25-year old male physician who is trying to improve his fitness levels and increase his muscular strength. he hires ariel (a personal trainer whom he is very attracted to) to coach him for two mornings each week, and completes two workouts on his own in the evenings. when he looks through his notes on his progress, he notices that when he works out with ariel he lifts heavier weights than when he works out on his own. he thinks that his performance with ariel could be related to increased testosterone. how could bias related to short-term maturation effects explain john's changes in strength? a. the natural variations in john's testosterone levels correspond with the times that he works out with ariel, which could temporarily increase strength. b. ariel's expectations of john's ability and masculinity affect how she observes his muscular strength and writes about his progress. c. john is attracted to ariel, wants to impress her, and believes that she wants him to lift heavier weights, which temporarily increases testosterone and observed strength. d. repeated testing of john's strength leads to extreme measurements when he works out with ariel, but these measurements become more normal over time.