Final answer:
The Robusta species of the coffee tree is more resistant to disease and yields more coffee than the Arabica species.
Step-by-step explanation:
The two main species of the coffee tree are Arabica and Robusta. Of the options provided, the one that is more resistant to disease and yields more coffee is a) Robusta. Unlike Arabica, Robusta coffee can withstand harsher conditions and is generally considered more resilient against pests and diseases. Robusta coffee trees also tend to produce beans that are less acidic and more bitter than those from Arabica trees.