Which plan was called as Mahalanobis plan named after the well known economist ?

Which plan was called as Mahalanobis plan named after the well known economist ?
 a) First plan 1951 to 1956
 b) Second plan 1956 to 1961
 c) Third plan 1961 to 1966
 d) Fourth plan 1969 to 1974

Second plan 1956 to 1961