The Greek Revolution, also known as the Greek War of Independence (1821-1832), primarily focused on the struggle for independence from Ottoman rule and had profound socio-political impacts. However, among the options provided, none directly correlate to effects of the Greek Revolution.
If the question is about the effects of the Greek Revolution on agriculture or environmental aspects, the most plausible indirect effect might be a temporary decrease in agricultural produce (A) due to the chaos and conflict during the war. The revolution caused disruption in farming practices and rural life, which likely impacted agricultural output during that period.
The other options (B, C, and D) do not have historical connections to the Greek Revolution directly. The shrinkage of the Aral Sea, changes in fish populations, and decreases in pollution are related to different environmental and geopolitical contexts.
Therefore, the most relevant answer to the effects of the Greek Revolution from your list would be:
A. Decrease in agricultural produce.