Which of the following, when paid to manage investments that produce taxable income, is a deductible expense?

The deductible expense among the options provided relates to the cost incurred for traveling to attend a shareholders' meeting. This expense can be deemed necessary and ordinary in the course of managing investments that produce taxable income. The Internal Revenue Service (IRS) allows taxpayers to deduct travel expenses for business purposes, including attending meetings where decisions affecting investments are made. This reflects the principle that expenses integral to maintaining and managing a portfolio can be deducted.

In contrast, commissions paid on sales of stock are typically considered part of the cost basis of the investment rather than a separate deductible expense. The cost of attending an investment-related seminar, while potentially beneficial for investment knowledge, is usually not deductible unless it qualifies as a business cost related directly to earning income. Similarly, the cost of investment advice often falls into a gray area depending on the circumstances and whether it is directly tied to the production of taxable income, but it is generally not treated as a deductible expense because it is often viewed as a personal expense, not directly linked to managing taxable income-generating investments.