A 2019 article in the American Journal of Public Health (AJPH) reports the results of a randomized study designed, as per the researchers, to "assess the effect of 2-way short message service (SMS) with a nurse on postpartum contraceptive use among individual women in Kenya". The reported results include the following prose:

"We randomized 260 women to 2-way SMS or control. At 6 months postpartum, 69.9% of the 130 women receiving SMS reported postpartum use of highly effective contraceptives (HEC), compared with 57.4% of the 130 women in the control arm".

.In this the study, the estimated relative risk of HEC use at 6-months postpartum for the women in the 2-way SMS group compared to the women in the control group is approximately:

a. - 0.125

b. 0.82

c. 1.22

d. 0.125