Water at 4 degrees centigrade has the highest density of all other water temperatures. This is why ice (whose temperature is below 0 degrees) floats on very cold water. This phenomenon is significant in the Artic and Antarctic where ice shelves float on cold ocean waters in the poles. Animals that live in these regions (such as seals and polar bears) use these ice shelves as hunting platforms. 
 
        
             
        
        
        
The first living things on Earth, single-celled micro-organisms<span> or microbes lacking a cell nucleus or cell membrane known as prokaryotes, seem to have </span>first<span> appeared on </span>Earth<span> almost four billion years ago, just a few hundred million years after the formation of the </span>Earth<span> itself.</span>
        
             
        
        
        
Answer:
The correct answer is - regulation of the heavy metal and their toxicity.
Explanation:
Metallothionein is a group of cysteine-rich, small in size, and highly conserved proteins that bind to various metal ions and regulate their activity or toxicity in transcriptional level.
Metallothionein IIA is one of the metallothioneins that binds to heavy metal and helps cells to be protected from the toxicity of these heavy metals. These proteins are present in almost every eukaryotic organisms virtually. These proteins are highly induced to express highly in the present of heavy metals.
Thus, the correct answer is - regulation of the heavy metal and their toxicity.
 
        
             
        
        
        
Answer:the answer is B hope this help
Explanation: