Answer C

“Their . vision was reinforced by specialized skills involving . swamp reclamation and irrigation systems, which . helped lay the foundation for the now well–known . and prosperous agribusiness of the region.” Hi I am not an instructor but I will try to help. The above line reference supports the correct answer D) knowledge of agribusiness practices. According to the line reference, the author refers to agribusiness of the region as “now well-known and prosperous.” Also, the author states that “specialized skills” helped lay the foundation for the “now well known and prosperous agribusiness of the region.” This implies that knowledge of agribusiness practices was developed later, not contemporaneous to the time when Chinese settlers initially interacted with the landscape of the Pacific Coast of US. Therefore, D) is our correct answer. I hope that I explained it correctly. Please feel free to correct me. Thank you.

If you look at lines 50-52, the passage states that the Chinese settlers had "specialized skills involving swamp reclamation and irrigation systems." Thus, C is in the passage, so we can get rid of this choice.