Option 1 -> "in accord with" typically refers to agreement with principles or standards, not proportional relationships.
Option 2 -> "in coordination with" means working together or collaborating, which doesn't fit the context of proportionality.
Option 3 -> "in balance with" is not a standard English idiom.
Option 4 -> "in keeping with" is the correct idiom meaning consistent with, appropriate to, or proportionate to.
Hence, Option 4: keeping -> "In keeping with" is a standard English expression used to indicate that something is appropriate to, consistent with, or proportionate to something else. In this context, it correctly conveys that the salary is proportionate to the amount of work performed. -> correct