Explanation:
In this sentence, the phrase "In order that" is the correct choice for completing the sentence.

Market Economy:
A market economy is an economic system in which economic decisions and the pricing of goods and services are guided by the interactions of a country's individual citizens and businesses. In a market economy, the laws of supply and demand, rather than government intervention, determine the allocation of resources and the distribution of income.

Maximizing Benefits and Minimizing Risks:
To ensure that a market economy is effective, it is important to maximize its potential benefits and minimize its risks. This can be achieved through various measures and strategies.

In order that:
The phrase "In order that" is used to indicate purpose or intention. In the context of the sentence, it implies that certain actions or steps need to be taken to ensure that a market economy becomes effective and its benefits are maximized while the risks are minimized.

Completing the Sentence:
The sentence states that "a market economy will become effective." This implies that there are certain conditions or requirements that need to be met for this to happen. The phrase "In order that" is the most appropriate choice to introduce these conditions or requirements.

By using the phrase "In order that," the sentence can be completed as follows:

"In order that a market economy will become effective, potential benefits should be maximized and risks minimized."

This completion of the sentence conveys the idea that there are certain actions or measures that need to be taken to ensure the effectiveness of a market economy. These actions include maximizing the potential benefits and minimizing the risks associated with a market economy.

Overall, the phrase "In order that" is the correct choice in this sentence as it accurately conveys the purpose or intention of taking actions to maximize the benefits and minimize the risks of a market economy.