I am really stuck here. I selected B . Below is my reasoning for the same.

demand of wine has not increased [This means it's either static or not decreased.]
last 3 yrs, price and production is also stable [lets call it no profit no loss.]

last year there profit increased by 10%. means something happened there. this is EXCEPT question so except one all will explain this.

A - Consumers in many countries increased their home stockpiles of bottles of wine, yet their overall consumption of wine decreased. -- if you increase home stockpile even if you are not drinking it will bring a profit to the producer. suppose a person drink 10 bottles in whole yr. and he stockpiled >=10. [profit]
if he stockpiled less then 10 then loss. --- still some profit is there so i kept it as profit in cases.

B - Wine producers have saved money on wages by switching from paying laborers an hourly wage to paying them by the amount harvested. --- suppose they pay $10 per hr, for 100 hrs harvesting work. now they pay one time.
after negotiations it turn out to be $1000. [no profit cases], paying hr. is more profitable anyways then later one.[i suppose this is not helping us.]

C - The price of oil, the major energy source used by wine producers in harvesting their crops, dropped by over 20 percent. --- profit in transportation, make sense.

D - Many small wine producers joined together to form an association of wine producers and began to buy supplies at low group rates. --- some how it is smelling profit to me.

E - Rainfall in wine-producing regions was higher than it had been during the previous year, allowing the growers to save money on expensive arti�cial irrigation. --- saving some money in producing harvests [profit]

confused in A and B. both can be partial answers. even though if i have to select i will go with B.

Experts, any help will be most appreciable.

Thanks in advance.

Thanks ceilidh . That is making some sense to me now

Below is the link for the same.
https://www.gmatfree.com/module-83/wine-profits/

gkkk wrote:Below is the link for the same.
https://www.gmatfree.com/module-83/wine-profits/

You might as well solve the actual GMAT question that this one is based on (Q51, OG 2016).

Contrary to earlier predictions, demand for sugarcane has not increased in recent years. Yet, even though prices and production amounts have also been stable during the last three years, sugarcane growers last year increased their pro�ts by more than 10 percent over the previous year's level.