Please consider the following sentence
"Oh my god, bad opening for the day", the shopkeeper ____ while seeing the trouble making customer and flashed a smile when customer approached him.
Which word of the below suits for the blank. Please find the words along with dictionary meanings:
Whisper= speak very softly using one's breath without one's vocal cords, esp. for the sake of privacy
Murmur = a soft, indistinct sound made by a person or group of people speaking quietly or at a distance
Mutter = say something in a low or barely audible voice, esp. in dissatisfaction or irritation:
Mumble = say something indistinctly and quietly, making it difficult for others to hear
Seems to be all words are suitable for the blank.