Mesquite trees can grow in soil containing few nutrients. Once mesquite trees have been growing in an area for a certain amount of time, the soil is found to be enriched with nitrogen compounds, making it fertile enough for the growth of crops. Which of the following is probably true of mesquite trees? (A) They have a symbiotic relationship with nitrogen-fixing bacteria. (B) They obtain useable nitrogen directly from the atmosphere and pass it on to the soil. (C) They take in atmospheric nitrogen during photosynthesis and use it to build glucose molecules. (D) All of these are probably true