Tissues is the most basic organismal level, <span>which are groups of similar cells that act as a functional unit. </span>
The answer is chromosome
The chromosome is densly packed DNA.
They all need energy, food, and water. If we're talking about animals, then they need oxygen. If we're talking about plants, then they need carbon dioxide
They do not need parents. Some animals don't have parents the moment they are born (eg: sea turtles).
So based on all that, B seems like the best answer
Although recent studies suggest that posttraumatic stress disorder (PTSD) symptoms and pain may be related, the possible mediational role of depression in this relationship has not been examined. This study sought to examine this question in a sample of 130 male veterans seeking assessment or treatment for deployment-related PTSD. Results suggest that PTSD and pain are moderately related (r<span> = .29) but that this relationship is fully mediated by depression. Our findings have important clinical implications: Treatment of PTSD and pain in veteran populations should include careful assessment and regular monitoring of depression.</span>
