The urine is a sub-product of our metabolism, being excreted from the body to dispose of compounds, mostly urea. The medium composition of urine is 3% of urea and other compounds and 97% water. However, the amount of water will change depending on the amount of this liquid available in the body. During hot seasons, we tend to sweat more, trying to keep our bodies cooled. But sweating demands us to use the water available in our body, and we loose more water than in lower temperaures of the surrounding. Because of that, the urine may have a lower percentage of water, as we have less water available in our bodies. When we exercise or do some activity that demands more of our metabolism, our bodies also tend to heat and, therefore, we sweat, causing the same decrease in the percentage of water. Therefore, the correct answer is d) HIGH temperature of the sorroundings and HIGH amount of activity.