Fill in the blank with the most appropriate option
 

It was _________ hot that day and the cable suffered the brunt of the heat. 

Unbelievably 

The correct answer is Option (4) → Unbelievably

The most appropriate word to fill in the blank is unbelievably.

"Unbelievably" emphasizes the extreme nature of the heat, suggesting it was so hot that it was hard to believe, which fits well with the context of the sentence.

"It was unbelievably hot that day and the cable suffered the brunt of the heat."

The other words do not fit the blank as well.

• Treacherously means involving betrayal or deception.
• Acceptably means in an adequate or satisfactory way.
• Unfailingly means in a reliable or unchanging way, always.