Tom wrote various words in code in such a way that different digits represent different letters and the same digit represents the same letter. For example, the word $BALL$ was coded as $$3488$$. One of the words below was coded as $$6155491$$. Which one? 
Overseas Competition->Knowledge Point->Combinatorics->Logical Reasoning->Reasoning by Conditions->Complex Reasoning 
According to the pattern: the same digit represents the same letter, the code $$6155491$$ should represent a word with two same letters at the third and fourth place. 