The correct answer is C. Respiratory diseases (e.g.asthma).
High concentration hydrocarbon pollutants in atmospheric air can cause respiratory diseases such as asthma, bronchitis, and pneumonia. These diseases can be caused by the inhalation of pollutants, which can irritate the lungs and airways. Symptoms of respiratory diseases can include coughing, wheezing, shortness of breath, and chest pain. In severe cases, respiratory diseases can lead to death.
Option A is incorrect because cancer is a disease that can be caused by a variety of factors, including exposure to carcinogens. However, there is no evidence that high concentration hydrocarbon pollutants in atmospheric air are a major cause of cancer.
Option B is incorrect because silicosis is a lung disease that is caused by inhalation of silica dust. Silica is a mineral that is found in rocks, sand, and concrete. Exposure to silica dust can cause inflammation and scarring of the lungs, which can lead to respiratory problems and death.
Option D is incorrect because reduced crop yield is a problem that can be caused by a variety of factors, including drought, pests, and diseases. However, there is no evidence that high concentration hydrocarbon pollutants in atmospheric air are a major cause of reduced crop yield.