Final answer:
Option (b) To complete the passage correctly, the words 'though' and 'waste' should be used, indicating the feeling of effort not leading to success.
Step-by-step explanation:
The correct answer to complete the passage is: though, waste. The passage with the blanks filled would read: "It's hard to lose. When we lose, it feels as though all of our hard work has gone down to waste."
The word 'though' is used in this context to introduce a subordinate clause expressing a contrast with the idea that is in the main clause, and 'waste' conveys a sense of something being unused or not utilized as intended.