Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks 

     Light pollution is the existence of too much unwanted, artificial light in the environment. Too much light pollution has (5) _______ effects on people. It upsets ecosystems, has bad health effects, and wastes energy.

     In upsetting ecosystems, light pollution poses a serious threat in particular to night wildlife, having damaging impacts on plant and animal physiology. It can affect the migratory patterns of animals, change competitive interactions of animals, and cause physiological harm. The rhythm of life as we know it is controlled by the natural daily patterns of light and dark. (6) _______, the disruption to these patterns does harm to the ecological dynamics. 

     With respect to adverse health effects, many species, especially humans, are dependent on natural body cycles, and the production of melatonin, (7) _______ are regulated by light and dark (e.g., day and night). If humans are exposed to light while sleeping, melatonin production can be affected. This can lead to sleep disorders and (8) _______ health problems such as increased headaches, worker fatigue, stress, some forms of obesity due to lack of sleep and increased anxiety. Health effects are not only due to over-illumination or excessive (9) _______ of light over time, but also improper spectral composition of light.

Too much light pollution has (5) _______ effects on people