Moonflowers and Morning Glories are closely-related plants, but one blooms in the morning, and one blooms at night. They do very well living in
the same garden. How is their opposite timing for blooms helping
enhancing their chance of reproductive success?

Nature is alive and effective 24 hours a day. Moon flowers are nocturnal bloomers, best enjoyed by late night strollers and night owls.

Post sunset, these magnificent, light-reflecting white flowers bloom and glow all night long – hence their name. However, when the sun begins to rise, they close their perfectly perfumed flowers tightly shut. Although moon flowers are predominantly white, they are also available in rich reds and vibrant yellows, all of which will add contrast to your floral display.

Although extremely beautiful, several species of moon flowers are very poisonous. It’s therefore a good idea to exercise caution when choosing late night bloomers for your garden.

i think the answer is b.