请问什么是standard asset？

问题如下：

The existence of “stranded assets” is a specific concern among investors of:

选项：

A.energy companies.

B.health care companies.

C.property companies.

解释：

A is correct. A specific concern among investors of energy companies is the existence of “stranded assets,” which are carbon-intensive assets at risk of no longer being economically viable because of changes in regulation or investor sentiment.