![](https://lstatic.shangxueba.com/jiandati/h5/images/m_q_title.png)
According to ELF, all of the following are environmentally harmful except_____. [A
According to ELF, all of the following are environmentally harmful except_____.
[A] causing fire in the houses [B] expanding ski resort [C] doing research on animals [D] invading into animal habitats