The answer would be, A. It absorbs organic materials in the environment.
Hope it helps.
If you mean like using a credit card then my response might help. So when you to an atm you can transfer paper money into your credit card by answering the questions on the screen and you can also take a loan from the machine of paper money or money in your card soon resulting in returning the money that you borrowed. If this is a question about math then credit is a positive term. So if a question asks about a persons money then you know that the money they have is positive. I hope I helped although this is labeled as a history question. Good luck.
During Vietnam War, US troops had the advantage of superior firepower. The correct option among all the options that are given in the question is the fourth or the last option. The United States forces did have a superior firepower but they lacked geographic knowledge of the region. This was one reason that the Vietnam forces never let the US forces have a complete victory.
