For the unit digit, we have only 3 choice: 5,7,9
For the First digit, we have 4 choices: 6,7,8,9 as the number should be greater than 600000(this is a typo in the question or else 6 digit numbers will always be greater than 60000)

So now if we chose the first digit as 6 or 8 then we will have 3 choices(5,7,9) in each case for the last digit and we can make 3+3 = 6 combinations for the first and last digits.
But if we chose 7 or 9 than we will only have 2 choices(5,7or9) in each casefor teh last one and we can make 2+2= 4 different combinations.
So total number of combinations for first and last digits = 6+4 =10.
Once we have our first and last digit, we can fill 4 places with 4 digits in 4! = 24 ways

So total number of ways = 10*24 = 240

Answer: A
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