C为什么不对 为什么是brownfield 他没有在扩建中

问题如下：

The privatization of an existing hospital is best described as:

选项：

A.a greenfield investment B.a brownfield investment. C.an economic infrastructure investment.

解释：

Investing in an existing infrastructure asset with the intent to privatize, lease, or sell and lease back the asset is referred to as a brownfield investment. An economic infrastructure asset supports economic activity and includes such assets as transportation and utility assets. Hospitals are social infrastructure assets, which are focused on human activities.