consciousness is rooted in the midbrain
 
        
             
        
        
        
A benign tumour is generally not dangerous as they grow usually within a membrane in one space. They can however grow really big in a short space of time and can cause pressure on neighbouring blood vessels which can be dangerous. 
Metastatic or malignant tumours are dangerous and cancerous. After they grow, some cells break off and travel in the bloodstream to a different area of the body (usually the main organs) and forms a secondary tumour there. This keeps happening until the cancer has spread to all of the body. 
**_hope this helps**
        
             
        
        
        
The embryonic endoderm<span> develops into the interior linings of two tubes in the body, the digestive and respiratory tube. the </span>lining<span> of the follicles of the thyroid gland and the</span>epithelial<span> component of the thymus (i.e. thymic </span>epithelial<span> cells). Liver and pancreas cells are believed to </span>derive<span> from a common precursor.</span>
        
             
        
        
        
Answer:
Sound Waves travel fastest through the Solid medium which is why Option 1 would be correct!
Hope this helps! :)