The principle allows a civil suit to be filed at the place where the defendant resides, where the defendant carries on business, or where the cause of action arises. A carries on business in Gurgaon and B carries on business in Mumbai, but B's agent purchased the goods and took delivery in Gurgaon, which is where the cause of action arose. A wants to sue B for payment.
Because both the defendant's business location and the place where the cause of action arose are available grounds under the principle, and each points to a different city, A has a choice between Mumbai and Gurgaon.
Therefore, the correct answer is At either of the places i.e. Mumbai or Gurgaon.
The decisive fact set here is that two separate grounds under the principle are both satisfied at once, B carries on business in Mumbai, and the cause of action, the purchase and delivery through B's agent, arose in Gurgaon. Each option can be tested simply by counting how many of those two grounds it accounts for.
Counting the valid grounds and matching them against each option leaves only the one that captures both Mumbai and Gurgaon together.
Therefore, the correct answer is At either of the places i.e. Mumbai or Gurgaon.