The attraction to real estate sales is the ____________ capital investment.

In the context of real estate sales, the correct choice highlights that the capital investment required to start a career in this field is relatively low, especially compared to other business ventures. Real estate agents often do not need to purchase properties upfront themselves, meaning they can begin their careers with minimal personal financial commitment. This lower barrier to entry makes real estate sales an appealing option for many individuals looking to enter the workforce or switch careers.

When evaluating why the other options are less suitable, it's worth noting that the terms "high," "significant," and "minimal" imply a level of financial input that does not align with the typical entry into real estate sales. While there are certainly costs associated with becoming a licensed agent, such as education, licensing fees, and marketing expenses, these costs are relatively manageable compared to the substantial investments required in other industries, such as starting a brick-and-mortar business or investing in rental properties. This is also why many people find real estate sales attractive—it allows them to leverage their skills in a market without needing extensive upfront capital.