I believe B. Is the correct choice. When using the word " Oh" in a sentence, it usually contains a comma before another statement.
Today we visited the largest desalination plant in the United States.
The Carlsbad Desalination Plant is located in the San Diego County in California and it's the largest plant currently operating in the United States. The first thing that struck me was how massive it looked, the thing is huge! Not only is massive in size, but also in how mucho clean water it generates, at 50 million gallons of clean water! As impressive as this number is, it only represents 7% of the total intake for the San Diego County.
It opened in 2015 and the construction took almost 14 years, the idea for this desalination plant began after 5 years of drought in California, and now mor than ever we need to make better use of our resources.
I loved the visit! I hope to visit it with my family anytime soon.
The relative pronoun is ''Which'' because relative pronouns connect to a clause or phrase to a noun or pronoun.
I thnk it might be C, but 100% sure.
