Given the task definition and input, reply with output. In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: a 1 k . m . long wire is held by n poles . if one pole is removed , the length of the gap becomes 12 / 3 m . what is the number of poles initially ?
Options: a ) 500 , b ) 501 , c ) 502 , d ) 503 , e ) 504
b