Under the Investment Company Act of 1940, a "redeemable security" is defined as a security that entitles the holder to receive their proportionate share of the issuer's net asset value (NAV) upon presentation to the issuer. Unit Investment Trusts (UITs) are a type of investment company that issues redeemable securities. The trust's sponsor is obligated to redeem the units from the investor at the current NAV. This characteristic distinguishes them from securities that trade on the secondary market, where prices are determined by supply and demand rather than by the issuer's NAV.

A. Short-term paper is explicitly excluded from the definition of a redeemable security in the Investment Company Act of 1940.

B. Master limited partnerships (MLPs) are publicly traded partnerships whose units trade on exchanges; they are not redeemable by the issuer at NAV.

C. Shares of a closed-end investment company are not redeemable by the fund; they are traded on the secondary market between investors.

1. Investment Company Act of 1940, Section 2(a)(32). This section defines a redeemable security: "‘Redeemable security’ means any security, other than short-term paper, under the terms of which the holder, upon its presentation to the issuer...is entitled...to receive approximately his proportionate share of the issuer’s current net assets, or the cash equivalent thereof." This directly supports the core definition and excludes option A.

2. U.S. Securities and Exchange Commission (SEC), Investor Bulletin: An Introduction to Unit Investment Trusts (UITs), (February 2013). This official SEC publication states, "UITs are redeemable, which means that a unitholder may sell his or her units back to the UIT sponsor at any time at the approximate net asset value..." This directly confirms that UIT shares (Option D) are redeemable.

3. U.S. Securities and Exchange Commission (SEC), Investor Bulletin: Mutual Funds and Exchange-Traded Funds (ETFs) - A Guide for Investors, (January 2012). This guide explains the structure of closed-end funds: "Unlike mutual funds, closed-end funds generally do not continuously offer their shares for sale. Rather, they sell a fixed number of shares at one time...After the initial offering, the shares of a closed-end fund typically trade on a stock exchange...The price of a closed-end fund’s shares on the stock exchange is determined by the market." This confirms why option C is incorrect.