The practice that involves short-term trading of mutual funds seeking to take advantage of short-term discrepancies between the price of a mutual fund's shares and out-of-date values on the securities in the fund's portfolio is called.

A. Market Timing

Explanation:

Based on the information provided within the question it can be said that the term being described within the question is called Market Timing. Like mentioned in the question this term refers to a strategy of buying and selling different financial assets, usually by trying to take advantage of price discrepancies in the short term.