The correct answer is D) suing the strip mall development in the court system.
The step the group would not be able to take is "suing the strip mall development in the court system."
The interest group Environment United would like to ensure a state law is passed to protect a local species of bird from a local developer who wants to build a strip mall.
The local developer has the project but until this moment, it hasn't done anything wrong to be sued on the court. That is why the interest group is not able to sue the strip mall development in the court system. What the group can do is to generate some actions on its favor such as donating unlimited amounts of money to individual candidates who support the group’s proposed law, lobbying public officials to vote in favor of the law or campaigning on behalf of candidates for public office who support the group’s proposed law.