D. 1,200
This is because if it takes 1 and a half hours **1.5** to travel through city a and city b , and the plane goes 800km per hour and 400km is half of that it then the answer has to be d.
The answer is A, a cell wall
A frog's lungs don't work that well, but since it's skin is so thin, oxygen and carbon dioxide can pass trough it.
Answer:
The immune system is closely associated with the lymphatic system
Explanation:
The endocrine system is a organ system that produce and secrete hormones all over the body. All the organ systems are interconnected and depend on each other and can be composed of different types of cells and tissues. But is it true that the immune system is closely associated with the lymphatic system because the lymphatic system rid the body out of toxins.
