According to the passage, which of the following is an argument for NOT blaming ash decline solely on ash yellows?
F. Most ash decline is caused by verticillium wilt, not ash yellows.
G. A study cited in the passage proves that only environmental factors have impacted ash decline in recent years.
H. A study mentioned in the passage shows that drought and weather may contribute to ash decline.
J. Verticillium wilt, ash yellows, and environmental conditions all contribute to ash decline equally.