Why are blueberries sour?

A common cause of sour blueberry fruit is over-production on a bush. If your bush is newly planted, you'll get sweeter, bigger berries if you remove all blossoms for the first year or two to allow the root system to establish. ... If blueberries are sour when picked, they will remain so.

Explanation:

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

the cold front replaces the warmer air at the ground level changing the wind to be breezy and denser.there is also an immediate drop in the temperature.