The Brazil Nut Tree, Bertholletia Excels (N = 17), Is

The Brazil nut tree, Bertholletia excels (n = 17) , is native to tropical rain forests of South America. It is a hardwood tree that can grow to over 50 metres tall, is a source of high-quality timber, and is a favourite nesting site for harpy eagles. As the rainy season ends, tough-walled fruits, each containing 8-25 seeds (Brazil nuts) , fall to the forest floor. Brazil nuts are composed primarily of endosperm. About $50 million worth of nuts are harvested each year. Scientists have discovered that the pale yellow flowers of Brazil nut trees cannot fertilise themselves and admit only female orchid bees as pollinators. The agouti (Dasyprocta spp.) , a cat-sized rodent, is the only animal with teeth strong enough to crack the hard wall of Brazil nut fruits. It typically eats some of the seeds, buries others, and leaves still others inside the fruit, which moisture can now enter. The uneaten seeds may subsequently germinate.
The same bees that pollinate the flowers of the Brazil nut trees also pollinate orchids, which are epiphytes (in other words, plants that grow on other plants) ; however, orchids cannot grow on Brazil nut trees. These observations explain ________.

A) the coevolution of Brazil nut trees and orchids
B) why Brazil nut trees do not set fruit in monoculture plantations
C) why male orchid bees do not pollinate Brazil nut tree flowers
D) why male orchid bees are smaller than female orchid bees