Sentence Correction

"One pervasive theory explains the introduction of breakfast cereals in the early 1900s as a result of the growing number of automobiles, which led to a decline in horse ownership and a subsequent grain glut; by persuading people to eat what had previously been horse feed, market equilibrium was restored."

As I write above, I dont understand what 'which' refers to in the sentence. Besides, it says "market equilibrium was restored", why?
Plz help...

"One pervasive theory explains the introduction of breakfast cereals in the early 1900s as a result of the growing number of automobiles, which led to a decline in horse ownership and a subsequent grain glut; by persuading people to eat what had previously been horse feed, market equilibrium was restored."

As I write above, I dont understand what 'which' refers to in the sentence. Besides, it says "market equilibrium was restored", why?
Plz help...

Which - "the growing number of automobiles"
Market equilibrium - " Cereals once fed by horses is eaten by humans "

Please correct me, if wrong.

Thanks,
GK

Logically, I can understand that "which" refers to "growing number of automobiles" but not sure if this line is can be considered right from the SC point of view. Since "which" will refer to "automobiles" alone.

Need experts comments.

Thanks.

gmatkiss is correct.