One crucial factor in the success of long-term marriages is:

A) a sense of agreement on everything.
B) a strong sense of shared experiences.
C) a more active sex life.
D) the trend toward living apart together.

A strong sense of shared experiences helps couples create a deep and meaningful connection with each other, which is crucial for the success of long-term marriages. Having shared experiences can also help couples navigate challenges and conflicts throughout their marriage. While agreeing on certain issues is important, it is unrealistic to expect couples to agree on everything. Having a more active sex life is not necessarily a crucial factor in the success of long-term marriages, as each couple's desires and needs in this area can vary. The trend toward living apart together is a relatively new phenomenon and is not necessarily a factor in the success of long-term marriages.