Whereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes form a random pattern.

• AWhereas in mammals the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, in birds the tubes  
• BWhereas the tiny tubes for the conveying of nutrients to bone cells are arrayed in mammals in parallel lines, birds have tubes that  
• CUnlike mammals, where the tiny tubes for conveying nutrients to bone cells are arrayed in parallel lines, birds' tubes  
• DUnlike mammals, in whom the tiny tubes that convey nutrients to bone cells are arrayed in parallel lines, the tubes in birds  
• EUnlike the tiny tubes that convey nutrients to bone cells, which in mammals are arrayed in parallel lines, in birds the tubes