<span><em><u>B. species.</u></em>
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The organismic hierarchy of organism comes from the highest and lowest order as the following;
<span>1. D Domain</span> <span><span>
2. </span>K Kingdom</span> <span><span>
3. </span>P Phylum</span> <span><span>
4. </span>C Class</span>
<span>5. O Order</span> <span><span>
6. </span>F Family</span> <span><span>
7. </span>G Genus</span>
<span>8. S Species</span>
This hierarchy and order helped many taxonomist to determine and classify organisms by a variety of criteria. And it seems that <em>species </em>can breed the same fertile offspring.
D to help the organism to reproduce
Rhythmic contraction and relaxation of heart is called <u>The</u><u> </u><u>Cardiac</u><u> </u><u>Cycle</u> .
I'd go with B because it makes sense to me.
Answer:
I want to say it's radiation but I'm not sure
