Step 1: Understanding Jurisdiction in Contract Cases:
Section 20 of the Civil Procedure Code provides that a suit may be instituted where the defendant resides or where the cause of action arises, either wholly or in part. In contract cases, the cause of action arises both where the contract is made and where it is to be performed or breached.
Step 2: Application of Legal Principle:
If a contract was made in one city and breached or to be performed in another, the plaintiff has the choice to file a suit in either of those places. This ensures fairness and convenience in legal proceedings.
Step 3: Final Conclusion:
Therefore, the correct answer is (D) Both (a) and (b), as a suit for breach of contract can be filed where the contract was made or where it was to be performed or breached.