According to Gupta (2018), what was the primary issue regarding the attempt to genetically modify taro?

a. GMO taro is produced on prime farmland which residents argue could be better used growing edible crops.
b. In initial studies, the genetic modifications made the taro plants highly toxic to humans and animals.
c. Taro is considered sacred to Native Hawaiians who objected to the idea that it could be modified and owned under patent law.
d. A study showed substantial GMO contamination of all taro production likely due to windborne pollen and insects.
e. The genetic modifications focused on increasing yield and not on preventing ringspot virus.