As shown below, this argument starts with two conditional premises that share a sufficient condition:

If the garlic is in the pantry, it’s fresh.
If the garlic is in the pantry, the potatoes are on the basement stairs.

The argument adds that one of the necessary conditions isn’t met: The potatoes aren’t on the stairs. Like the stimulus, (A) takes the fact that one necessary condition has failed to guarantee that the other necessary condition—the garlic is fresh—isn’t met, either. But that’s not a valid conclusion!

No flaw. This is a valid argument! If the jar is held over the burner for 2 minutes, it reaches optimal temperature; at optimal temperature, the contents of the jar liquefy immediately. The har was held over the burner for 2 minutes, so we can follow the chain of conditional claims to conclude that the contents liquefied immediately!

No flaw. This is a valid argument! If a book was set with wooden type, then it’s over 200 years old; if it’s over 200 years old, it’s classified “special.” This book wasn’t classified “special,” so we can take the contrapositives back through the chain of conditional claims to validly conclude that the book wasn’t printed with wooden type.

Wrong flaw. (D) reaches its conclusion via a mistaken belief that a negated sufficient condition guarantees a negated necessary condition: “won’t operate” is a necessary condition of “foot pedal depressed,” so when (D) says the foot pedal isn’t depressed, it’s negating the sufficient condition to erroneously conclude that the necessary condition must also be negated. Unlike the stimulus, (D) is structured as a chain of conditional claims, rather than two conditional claims that share a sufficient condition.

No flaw. This is a valid argument! If the kiln is too hot, then the plates will crack; if the plates crack, the artisan must redo the order. The artisan doesn’t have to redo the order, so we can take the contrapositives back through the chain of conditional claims to validly conclude that the kiln wasn’t too hot.