Use the Following to Answer Questions

Use the following to answer questions
Scenario III
Scenario III is based on fabricated data inspired by the following study:
Cobeya, K. D., Buunka, A. P., Robert, S. C., et al. (2012) . Reported jealousy differs as a function of menstrual cycle stage and contraceptive pill use: a within-subjects investigation. Evolution and Human Behavior, 33, 395-401.
Effect of Hormone Level on Female Jealousy
The purpose of this study was to examine female jealously over the course of one's menstrual cycle. To that end, 29 females between the ages of 20 and 33 years were recruited from a reproductive health clinic via word of mouth. The women completed a jealousy scale via computer from their home on three separate occasions. The first occasion was when women were taking the birth control pill. After not having taken the pill for at least two months the women completed another two jealousy surveys, once during ovulation when they were fertile, and again when they were in the luteal cycle and not fertile. Fertility (and lack thereof) was determined by ultrasound. Of the 29 women who started the study, only 17 completed the study. The mean level of jealousy of the remaining 17 women at the time of each test was compared. The results indicated a statistically significant effect of time of survey on jealousy. Women, regardless of relationship status, were significantly less jealous when they were not fertile than when they were fertile.
-(Scenario III) The researchers of the study described in Scenario III offered participants an iPhone or the equivalent in cash after they completed the study. Why do you think they did this?

A) to minimize attrition
B) to reduce maturation
C) to minimize testing effects
D) to reduce instrumentation