Read the passage.

The town council of Hopewell has proposed that the vacant lot at the end of Elm Street be converted into a parking lot. While this unused land may seem like a suitable location, the nearby residents have many objections. For example, the youth in nearby neighborhoods enjoy using the lot for recreation. Many pet owners appreciate the undeveloped land because it allows dogs a place to run. Adding cars and pavement to this cherished natural area would be a grave error. The town council should observe the lot and all its uses before taking action.

Which phrase best reveals the author’s viewpoint?

suitable location
adding cars
grave error
take action

grave error