Final answer:
Direct foreign investment offers a company the most control and highest potential return due to its long-term focus and managerial involvement.
Step-by-step explanation:
The mode of foreign market entry that offers the most control and the highest potential return for a company is direct foreign investment. This mode involves purchasing more than ten percent of a company and usually comes with managerial responsibilities. Foreign direct investment has a long-run focus and is less liquid compared to portfolio investments, meaning it is more difficult to divest quickly. However, this increased control and presence in the foreign market often leads to higher potential returns and greater influence over operations.