Step 1: Understand the question.
The parties did not agree on the place of arbitration. We must find what the tribunal looks at under Section 20 of the Arbitration and Conciliation Act, 1996.
Step 2: Know why the place matters.
The place (seat) of arbitration sets the procedural framework for the case. So choosing it is important.
Step 3: Recall party autonomy.
The Act lets parties freely choose the place. This is the principle of party autonomy. The parties decide first.
Step 4: Apply Section 20 when parties do not agree.
If parties fail to agree, the tribunal fixes the place. It must do so by looking at all the circumstances of the case, including the convenience of the parties.
Step 5: See the factors used.
The tribunal may weigh the convenience of the parties, where witnesses are, the kind of evidence, the cost, practical difficulties, and the interests of justice. The law uses wide words on purpose.
Step 6: Check the options and answer.
Civil court jurisdiction alone, the place the contract was signed, and the location of the subject matter are not the statutory test. Only option 3 repeats the language of Section 20, stressing circumstances of the case and convenience of the parties.
\[ \boxed{\text{Circumstances of the case, including the convenience of the parties.}} \]