Question

Choose the most logical order of sentences from among the four given choices to construct a coherent paragraph. (

Q: Answer-Choose the most logical order of sentences from among the four given choices to construct a cohere...

D introduces the topic of the avian respiratory system and the unique structure of bird lungs.B follows by describing how the air sacs in birds allow unidirectional flow of air through the lungs, which builds on the previous information.A explains the benefit of unidirectional flow, i.e., the air remains fresh with higher oxygen content.C contrasts this with the bidirectional airflow in mammals, providing a comparison to birds.So, the correct sequence is DBAC.

A Unidirectional flow means that air moving through bird lungs is largely 'fresh' air & has a higher oxygen content. (
B The air sacs permit a unidirectional flow of air through the lungs.(
C In contrast, air flow is 'bidirectional' in mammals, moving back and forth into and out of the lungs.(
D The avian respiratory system is different from that of other vertebrates, with birds having relatively small lungs plus nine air sacs that play an important role in respiration (but are not directly involved in the exchange of gases).