Option 1 -> "with" suggests collaboration or accompaniment, which doesn't fit when describing constraints or circumstances.
Option 2 -> "for" implies working to achieve or in favor of the conditions, which contradicts the negative context.
Option 3 -> "from" would suggest working away from or starting from these conditions, which is not idiomatic.
Option 4 -> "under" is the correct idiomatic preposition used to describe working within certain circumstances or being subjected to particular conditions.
Hence, Option 4: under -> "Working under these conditions" is the standard English expression for operating within or being subjected to particular circumstances or constraints, especially unfavorable ones -> correct