Option 1 states that forced labor (Vishti) became more common than before in the Gupta period. This is a correct statement. The Gupta period marked an increase in the usage of forced labor to meet the growing demands of the empire.

Option 2 mentions a passage in the Vishnu Purana that refers to the Guptas enjoying all the territories along the Ganga up to Prayaga. This is a correct statement. The Guptas did have control over a vast territory along the Ganga and are known to have expanded their empire in various directions.

Option 3 refers to the Mehrauli inscription which suggests that Chandragupta, the Gupta Emperor, fought against a confederacy of enemies in Bengal and led a campaign into the Punjab. This is a correct statement. The inscription provides evidence of Chandragupta`s military campaigns and his efforts to expand the empire.

Option 4 states that Saurashtra was not a part of the Gupta Empire. This is the correct answer. Saurashtra, a region in western India, was not under the control of the Gupta Empire. The Guptas focused their expansion in other directions and did not have control over Saurashtra.

In conclusion, option 4 is the correct answer as Saur