Answer :
D
Sound travels best in dense air because the molecules are close together than in less dense air.
Explanation:
Because the air is compressed in the balloon, the air molecules inside are closer together than the air molecules outside the balloon. Therefore these molecules inside the balloon can transmit the sound energy effectively. Remember sound waves are made by the transmission of the compression and rarefaction by the air molecules.
This is also the reason why solids are good transmitters of sound waves (and other mechanical waves) than air. The molecules of solids are more closely packed than those of air.
Learn More:
For more on sound transmission check out;
https://brainly.com/question/13883327
https://brainly.com/question/2234779
https://brainly.com/question/61859
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Correct answer is D
Sound does not travel around the air outside of the balloon as well as it does through the denser air pressure inside the balloon. Sound waves travel better through denser material.