By Clara Denina LONDON (Reuters) – Rio Tinto has only bad options as it tries to salvage its $2.4 billion Serbian lithium project after the country’s leaders bowed to environmentalists and cancelled it last week. The Anglo-Australian miner could sue the government, a step likely to fail and further antagonise Belgrade, or bet that pro-mining politicians emerge victorious in April parliamentary elections, a result that would embolden opponents. The mining titan has little experience charting where to go next. People inside Rio said that while they were aware of the political tensions around the…