Option (a) save (ƒa), save (ƒb), save (ƒd), delete (ƒd), save (ƒc) is possible as we can save 1,3,6 in 9 contiguous block and then delete ( fd) to get 6 contiguous space. After that we can save ( fc ) = 5 in remaining 7 blocks.. So option (a) is possible.
Similarly we can execute Option (c) and option (d) where as option (b) is not possible