In Paragraph 4, the pronoun "it" refers to ______.

A．The seeds Diana' s grandfather gave her before death inspired the couple to start the organization.
B．Heritage Farm' s collection not only includes plant seeds from Western Europe.
C．Only members of the organization have access to the plant seeds in its collection.
D．Members of the organization are offered information as to what plants they can buy from other members.

A．searching different sources of food supplies throughout the world
B．collecting various plant seeds, like vegetables, fruits, grains, flowers and herbs
C．the existence of a large variety of rare plants and animals in a given place at a given time
D．the existence of a wide range of different types of plants and animals in a given place at a given time