The atmosphere
Is not a reservoir for phosphorus.
The answer for the question is the Apical meristem.
Growth in plants occurs as the stems and roots lengthen. Some plants, especially those that are woody, also increase in thickness during their life span. The increase in length of the shoot and the root is referred to as primary growth. It is the result of cell division in the shoot apical meristem.
Your answer would be A. Uracil
It’s a huge typhoon-like storm of swirling gasses. A long-lived, oval cloud circulation similar to a hurricane on Earth.