Question

Palm oil, produced from palm trees, is not only a
biofuel, but is also used in food additives,
cosmetics, and lubricants. Palm tree plantations
are now cultivated in areas that were formerly
natural forests. One ecological concern raised by
this expansion is that
(1) the natural forest ecosystem may harm the
palm trees
(2) the use of the land for agriculture will
increase the biodiversity of the area
(3) humans are changing the basic processes of
the palm trees
(4) planting large expanses of one crop reduces
the biodiversity of the area

Answer 1

The correct answer to your question would be (4) - planting large expanses of one crop reduces the biodiversity of the area.

This should be evident - once you're planting only one crop in a certain area this necessarily decreases the biodiversity of that area. What is even more problematic with palm oil, however, is that it's often associate with the reduction of the natural habitat of different animals such as orangutans for example.