I am not sure because there may be more context, but here is what I am guessing the answer is.
As Bryson pedaled uphill both his heartbeat and breathing rate increased. His breathing rate increases to provide the body (more specifically, exercising muscles) with oxygen at a higher rate and his heart rate increases to deliver the oxygen (and glucose) to the respiring muscles more efficiently.
Answer:
2
Explanation:
The most simple viruses have only two parts: 1) a genome (DNA or RNA) that is a blueprint with instructions for making more viruses and 2) a capsid protein shell that protects the genome.
Carbs contain lots of energy, so not A.
They are different carbs with different atom arrangements, so not B.
And carbs only contain 3 elements C, H, and O.
So the answer should be C.
Im really good at crosswords, e-mail a copy & i’ll fill it out for you