The respiratory system contains the lungs, so the answer is C. Hope this helps.
Answer:Enrico must multiply the distance of mars from sun (meters) with the
to convert the distance in astronomical units.
Explanation:
1 astronomical unit = 

Let the distance between the sun and Mars be Y( meters)
Distance in AU= 
Enrico must multiply the distance of mars from sun (meters) with the
to convert the distance in astronomical units.
Interphase: Chromosomes duplicate, and the copies remain attached to each other.
Prophase: In the nucleus, chromosomes condense and become visible. Spindle fibers begin to form.
Prometaphase: The nulcear membrane breaks apart, and the spindle starts to interact with the chromosomes.
Metaphase: The copied chromosomes align in the middle of the spindle.
Anaphase: Chromosomes separate into two genetically identical groups and move to opposite ends of the spindle.
Telophase: Nuclear membranes form around each of the two sets of chromosomes, they begin to spread out, and the spindle begins to break down.
Cytokinesis: The two cells split into two daughter cells, each with the same number of chromosomes as the parent cell.
<span>Secondary succession is faster than primary succession because the soil is already there and the soil usually contains many seeds.</span>
<span>The correct answer is ‘gametes’. Gametes are sex cells: male gametes are sperm cells and female gametes are egg cells. Gametes each contain one set of chromosomes, and when fertilisation occurs, they form a diploid cell.</span>