Option A - incorrect
The phrase 'a significant occurrence of ask blight increase' in this option implies that there's one event or an 'occurrence' of oak blight increase, which makes it seem as if it spiked for a single moment. This doesn't explain the intended meaning which is the fact than an increase takes place over time not once.
Option B - incorrect
The modifier 'caused by glowing fungus resistance against herbicides' modifies the phrase 'oak blight' which explains that oak blight was caused by a fungus resistance, not the fungus itself.
Option C - incorrect
This option has a very similar issue with option A; it says that there has been a single 'increasing oak bright occurrence,' once again implying a single event or occurrence of the blight.
Option D - correct
The phrase 'due to' explains the intended meaning of the sentence. It describes how the increase in oak blight was caused by the glowing resistance of fungus to herbicides.
Option E - incorrect
This option has the same issue as option A. It implies that the occurrence of oak blight only happened once and it was over.