The correct answer is the first one: "Problems Caused by Alcohol", since the first purpose of the Woman's Christian Temperance Union was to create a "sober and pure world" by abstinence, purity and evangelical Christianity, as a matter of fact, the constitution of this organization called for the entire prohibition of the manufacture and sale of intoxicating liquors as a beverage.
The word "Temperance" means: moderation in all things healthful and total abstinence from all things harmful, in other words, should something be good, it should not be indulged in to excess and should something be bad for you, it should be avoided altogether.
To sum up, they saw (and still see) a huge danger in alcohol.