Final answer:
The means of diversification into a real estate security provided by the options is a Real Estate Investment Trust (REIT), which is a company that owns, operates, or finances income-producing real estate, offering diversification and income through dividends.
Step-by-step explanation:
The means of diversification into a real estate security while continuing to hold a real estate investment among the options given is Real Estate Investment Trust (REIT). A REIT is a type of company that owns, operates, or finances income-generating real estate. Investing in a REIT allows an investor to gain exposure to a portfolio of real estate assets, which can spread risk through diversification. REITs generate income for investors through dividends which are derived from the income the properties earn.
Other investment vehicles mentioned like Real Estate Option and Real Estate Futures Contract are typically used for speculative purposes or hedging and do not represent ownership in a diverse portfolio of real estate assets. A Real Estate Exchange-Traded Fund (ETF), similar to a REIT, can offer diversification as it invests in several real estate companies or REITs; however, it is not a direct investment in real estate, but rather a collection of stocks related to real estate companies that is traded on an exchange.