Read the following passage and fill in each blank with words chosen from options given.
As he started his speech, Harsh was aware that people were listening to him quite (1) ______. Things seemed to be going quite well. (2) ______, halfway through the talk, he saw his friend, Ravi look ( 3) ______ his pal Sunil, roll his eyes and whisper in his ear. Harsh (4) ______ understood that Ravi, who had been upset ever since his promotion, was now (5) ______ disturbance intentionally.
Select the most appropriate option to fill in blank No.4