If statement indicates the presence of conditional statement.

"if the working classes controlled the economic system"- is a sufficient statement. Now we need to find a necessary statement to fill the 'Then' clause.

Premise is those who control production treat working class to sub standard working conditions and extracts maximum prices from from consumer.

The conclusion is if the working class controlled the system then according to the passage, the above mentioned problems should not result.

Lets look at options:

a. The owners of the means of production could not be depended upon to charge as much as necessary for their products to enable the owners to pay a fair working wage to laborers. [ clearly out of scope. this does not talk about the problems mentioned at all]

b. Market forces would cause the most successful commercial entities to monopolize the market. [ new topic. this question has to be treated like a must be true question. extra info other than what is given in the passage cannot occur]

c. Consumer goods would be less expensive. [Bang on! it expresses the problems that would not result. correct!]

d. The free market would favor producers who are able to provide the highest quality product at the lowest possible price. [ high quality with respect to low price is not mentioned in the passage at all]

e. Communist methods of production and distribution would still not replace the capitalist system, despite its costs to the working class. [new topic. out of scope]

Marxist theorists believe that the interests of the working class ultimately align with those of humanity in general. They claim that those who control the means of production are able to unfairly subject the working class to substandard working conditions and wages, while extorting the maximum possible prices for their products from consumers. Marxists therefore believe that if the working classes controlled the economic system, then __________.

Which of the following best completes the passage to the left?

a. The owners of the means of production could not be depended upon to charge as much as necessary for their products to enable the owners to pay a fair working wage to laborers.
INCORRECT : Dependence on owners of the production to charge for their products as necessitated to pay wages to laborers is irrelevant.

b. Market forces would cause the most successful commercial entities to monopolize the market.
INCORRECT : Additional/new information.

c. Consumer goods would be less expensive.
CORRECT : It defines the solution to the problems of working class (substandard working conditions & high product price) discussed in the Premise of the argument.

d. The free market would favor producers who are able to provide the highest quality product at the lowest possible price.
INCORRECT : Out of scope... issue is not about highest quality of product and lowest prices.... issue is about highest prices of products and low wages

e. Communist methods of production and distribution would still not replace the capitalist system, despite its costs to the working class.
INCORRECT : Clearly out of scope. There is no mention of communist methods of production and distribution etc in the argument.

The argument looks like,

P1. MT believe WC interests align with those of humanity in general.
P2. MT claim controllers (of production means) are able to
1. subject WC to substandard Work conditions and wages
2. extort max prices from the consumers.

Here the question is what happens if the WC controlled economic system

It is a must be true question, so you have to find some thing which is true according to information given in the passage,

A- whether they could be depended up on has already been stated in the argument directly.
B- Not supported by the stimulus
C- a definite answer from the premise P2-2
D- who would the free market favor has not been discussed in the passage
E- could not be true according to the information in the passage.