There are 7 places and 3 numbers to choose from. But, since it is a palindrome, first 3 digits will be same as last 3 digits. Further, first digit can not be zero and the fourth digit can be any of the 3 numbers.
So, effectively we have 4 places to be filled from 3 numbers in the following way,
First Digit: 2 ways (either 5 or 6)
Second Digit: 3 ways (5,6 or 0)
Third Digit: 3 ways (5,6 or 0)
Fourth Digit: 3 ways (5,6 or 0)
Total number of possible ways: 2x3x3x3= 54 ways
Ans: B
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