Increased in occupational specialization in industrial field
I feel like this is conditional but I'm not too sure, I would go with A because it is a perfect past tense while D is simple past tense (I would use D is normal conversation though)
D would be like answering a question "what did you do last night?" "I went to bed two hours before it started raining"
A is like you're telling someone what you have already done using active voice "I had gone to bed two hours before it started raining"
Take what you will from this, my friend. Sorry I can't be more of a help
Answer:
If water and air deterioration have been described and studied for decades, soil contamination has become a priority only by late 1990s. Only in the last fifteen years, the importance of soil has been recognized as it represents the most important element for supporting life on Earth.2 Indeed, soil supports terrestrial ecosystems and human constructions, it regulates water cycle and carbon dynamics, decomposition takes place into the soil and the nutrients become available again. Soil provides food for human nutrition, and its quality represents a fundamental requirement for food safety, and therefore for animal and human health, even though not always this relationship is stressed enough
A. Read text out loud since you learn by hearing or listen to the text
Focus means to concentrate without distraction.
