Which of the following might be an indicator of global warming?
a. average increase in the temperatures near earth's surface
b. a decrease in greenhouse gases
c. average decrease in the temperatures near earth's surface
d. a decrease in carbon dioxide emissions

The Global Surface Temperature is Rising

NOAA states:Many lines of scientific evidence show the Earth's climate is changing. This page presents the latest information from several independent measures of observed climate change that illustrate an overwhelmingly compelling story of a planet that is undergoing global warming. It is worth noting that increasing global temperature is only one element of observed global climate change. Precipitation patterns are also changing; storms and other extremes are changing as well.

Bwould be my guess |-/ 

Asmall closed hole formed in an outwash plain or moraine. forms when a  glacier retreats then remains stationary.