The text cites two reasons why the percent of grandparent-maintained families are becoming more predominant. These factors are:

a. economic conditions are worsening and grandparents are living longer
b. economic conditions are getting better and grandparents are living longer
c. more children are being born to younger and younger parents and grandparents are living longer
d. more children are being born to younger and younger parents and grandparents are more likely to be divorced

a