I think 'which' modifies 'ornamentals'. Ornamentals have a value of $30 billion. It doesn't say Ornamentals with scent have a value of $30 billion. That's why I don't understand why D is the correct answer. Can you explain?
Unfortunately, traditional breeding has often produced cultivars with improved vase life, shipping characteristics, colour and shape while sacrificing desirable perfumes. The loss of scent among ornamentals, which have a worldwide value of more than $30 billion, makes them important targets for the genetic manipulation of flower fragrance.
Multiple Choice Question
The number of $30 billion quoted in the passage is to illustrate the fact that
A. favorable perfumes are made from ornamental flowers.
B. the cultivation of flowers needs to step out of its traditional ways.
C. genetically-modified aromas make for a profitable industry.
D. scent plays a significant role in ornamental industry.