Answer:

<h3><u>2</u><u>4</u><u>0</u><u> </u><u>is</u> the answer</h3>
Answer:
The purpose of the outer covering of the bird helps keep it warm and to help it fly, whilst the outer cover of the tree is to protect it from bugs.
Explanation:
Production of the mature sperm cells have 4 step process beginning at puberty and throughout the male's lifetime. Spermiogenesis is the final process for production of sperm where the spermatids mature into motile spermatozoa. For humans, the spermatogenesis takes 74 days to 120 days and if the transport on the ductal system is included it would take 3 months.
(The 3 examples are:)
~ CO2 from burning fossil fuels
~ gas (methane) leaks from underground gas pipes
<span>~ methane from rotting material in landfills
</span>
(Other ones)
<span>~ combustion of fossil fuels (oil, coal, and gas)</span>
<span>~ deforestation (decreasing amount of plants that remove CO2 from the atmosphere)</span>
<span><span>~ industrial production that uses petroleum based products (mineral/metal production)
</span></span>