In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].

When they met in an online IVF support group back in 2011, Andrea Rivas and Sandi Palmisano were two women struggling to get pregnant. They longed for children and believed if they could at least have one healthy baby each, they'd be happy. Fast forward four years and the two women from Martinsburg, West Virginia have six babies between them – three sets of twins. And all of them were carried by Andrea. Their story is a miraculous one of hope and friendship. In 2014 Andrea made headlines when she gave birth to Sandi's children EmmaLee and Grayson after agreeing to become a gestational carrier for Palmisano when a medical condition prevented her from carrying an embryo to term.Andrea Rivas and Sandi Palmisano, both from Martinsburg, W Va, met through an online IVF support groupAndrea, 30, and her husband Mark, 41, had twins through IVF but Sandi, 47, and her husband Philip, 45, failed in three cycles - then Andrea stepped in to become a surrogateBut months after giving birth to Sandi's twins, Andrea and her husband Mark conceived naturally - and amazingly were told they would have twins againShe gave birth in March almost a year to the day since giving birth to Sandi and Philip's twinsSandi tells Daily Mail Online: 'Between the two of us we have six babies. It's almost impossible to put into words.' 
 Question:'Never in a million years would it have occurred to me that _ would have offered to help us.'
Andrea Rivas