For a Vertebrate Animal to Obtain and Use Energy

Multiple Choice

For a vertebrate animal to obtain and use energy,

A) the digestive system is used to break down oxygen to be stored in cells.
B) the circulatory system must provide carbon dioxide to cells.
C) the circulatory,respiratory,digestive,endocrine,and nervous systems are some systems involved.
D) only one organ system,the digestive system,is needed.