वाक्य के उस भाग की पहचान करें जिसमें व्याकरणिक त्रुटि है: 'By the 19th century, (a) / several thousand stepwells (b) / have been built throughout India. (c) / No error (d)'

Identify the part of the sentence that contains a grammatical error: 'Had I knew the answer, I would have raised my hand.'

Identify the part of the sentence that contains an error: A bigger budget has been set aside for this years marketing campaign in Asia.