Option 1, Kodaikanal (Tamil Nadu) is an artificial lake. Indeed, the Kodaikanal Lake, also known as the Kodai Lake, is a man-made lake that was created in 1863 by Sir Vere Henry Levinge. The lake is considered one of the significant tourist attractions in Kodaikanal.

Option 2, Kolleru (Andhra Pradesh), is not an artificial lake but a natural one. It is one of the largest freshwater lakes in India, located in Andhra Pradesh, and recognized as a wetland of international importance.

Option 3, Nainital (Uttarakhand), also involves a natural body of water. The Naini Lake, situated in Nainital, got its form through tectonic activities and is not human-made.

Lastly, Option 4, Renuka (Himachal Pradesh) is another natural lake. It is considered the largest in Himachal Pradesh and is shaped like a reclining woman, which also adds religious significance to the lake.

Therefore, it is clear why the correct answer is Option 1, Kodaikanal (Tamil Nadu), as it is the only artificial or man-made lake among the given options.