Task: Question Answering
Input (English): Problem: employees of a certain company are each to receive a unique 8 - digit identification code consisting of the digits 0 , 1 , 2 , 3 , 4 , 5 , 6 , and 7 such that no digit is used more than once in any given code . in valid codes , the second digit in the code is exactly twice the first digit . how many valid codes are there ? 
Options: a ) 1220 , b ) 1840 , c ) 2160 , d ) 2480 , e ) 2760
Output (English): c