Question stem: Assumption
First sentence: Every action--->Consequence--->some other actions.
Second sentence: To know Good action---> to know good consequences, but We don't know the future (main premises), SO Good actions=impossible (conclusion)
Pre-thinking: "Every action--->Consequence--->some other actions". This guy is a cyclic condition and repeats itself limitlessly. So, We don't know its exact consequence. If we show that another way for knowing good action is impossible, the argument holds. Another way to know good action is to know it is good. But it is impossible as the argument says "Knowing good consequences reveals good actions". The answer is E.
Answer choices B and C are out for new irrelevant information.
(B) We can know that past actions were good.---> 'past actions were good' is new and Irrelevant. So OUT.
(C) To know that an action is good requires knowing that refraining from performing it is bad.---> "refraining from performing it is bad" is an extra new information. So, OUT.
(A) Some actions have only other actions as consequences. --> But what about other actions? 0<some<100% , some=1%, 2%, 3%, ..., 99%. So, Actions (100%)= some actions (from 1% to 99%)+the rest actions (100%-some).
Even if we evaluate some actions, we can't do anything to evaluate the rest actions. So, this guy is OUT.
(D) Only actions can be the consequences of other actions.-->This guy says, consequences=actions. But the argument says, Every action has consequences and among the consequences of any action are other actions. (consequences=some consequences in which no action stays+other consequences in which other actions stays)
(E) For an action to be good we must be able to know that it is good. -->This is valid