LONDON, June 20 (Reuters) - Glencore GLEN.L on Tuesday said it would review its options after Rio Tinto RIO.L RIO.AX said it was sticking to a recommendation of China-backed Yancoal YAL.AX as the preferred buyer of its Coal & Allied division in Australia. a statement, Glencore, which had made a higher offer than Yancoal, said it would respond "in due course".