The Inscription which proves Chandragupta's sway over western India is:

Detailed Solution:

The correct answer is “Junagarh Rock edict of Rudradaman”.

The Junagadh rock inscription of Rudradaman, also known as the Girnar Rock inscription of Rudradaman, is a Sanskrit prose inscribed on a rock by the Western Satraps ruler Rudradaman I. It is located near Girnar hill near Junagadh, Gujarat, India. The inscription is dated to shortly after 150 CE.

It mentions the construction of the Sudarshana Lake by Chandragupta. This lake was constructed by the order of Chandragupta Maurya, the founder of the Maurya dynasty by the Governor 'Pushyagupta Vaishya'.