Betty owns $60$ percent of the stock of Zello Corporation. Three unrelated individuals own the remaining $40$ percent. For a stock redemption of Betty's stock to be treated as an exchange under the "substantially disproportionate" test, what percentage of Zello stock must Betty own after the redemption?

Question $17$ options:

Any percentage less than $60$ percent

Any percentage less than $50$ percent

All stock redemptions involving individuals are treated as exchanges.

Any percentage less than $48$ percent