Alex can sue Emma for breach of contract and claim damages. When a contract is breached, the injured party has the right to seek remedies, including damages for any losses suffered. Option B is incorrect because Emma's right to a refund would depend on whether the misdescription constitutes a fundamental breach. Option C is incorrect because while Alex may keep the deposit as partial damages, he cannot claim both the deposit and the remaining balance without considering the breach. Option D is misleading as it oversimplifies the issue; the contract’s terms and any potential misrepresentation or misdescription would need to be considered. Option E is incorrect as Alex is not required to provide a replacement but may need to address any breach of terms regarding the car's description. 

Key Point: This question examines the remedies available for breach of contract, focusing on the enforcement of contractual obligations and the potential claims for damages.