Consider the following statements regarding Monuments of National Importance (MNI):

1. Monuments of National Importance (MNI) in India are legally protected under the Ancient Monuments and Archaeological Sites and Remains (AMASR) Act, 1958.

2. The Act empowers local self-government bodies to declare certain monuments as MNIs.

3. Within a 500-meter radius of the monument, construction activities are prohibited.

How many of the above statements are correct?