Read the following passage:

After tracking down the correct pipe fittings, I approached my final obstacle - the self-checkout. That was, allegedly, the quickest way out of this labyrinth, but I knew I wouldn't escape without a struggle. I began with the spray paint because it had the largest bar code. Beep! Beep! Charged twice for one item - the battle had begun!

Which words from the passage best create a combative tone toward the self-checkout?

A. approached, begun
B. tracking, Charged
C. final, escape
D. obstacle, struggle