Final answer:
The wives and concubines in the sultan’s harem were primarily kept as companions and to bear heirs, with significant political influence at times, especially during the Sultanate of Women era.
Step-by-step explanation:
The best statement that describes the wives and concubines in the sultan's harem is that "They were kept as companions and often provided heirs to the throne." Within the Ottoman harem, women were ranked in a hierarchy with the potential to rise through the ranks based on their talent and service. Wives and concubines could become influential, particularly if they bore the sultan children. In the broader perspective known as the Sultanate of Women, women related to the sultan, such as his mother or wife, wielded considerable influence over the court, often financially supporting public works and displaying their popularity and power.