Which word is abstract?

horse
playground
success
thunder

Sarah and juan were running in the school track meet. the muscles in their arms and legs them run fast. other muscles that you cannot see were also at work. the most important muscles for this track meet were the muscles in their a) arms. b) eye. c) feet. d) heart.

In the artwork "that gentleman" by andrew wyeth how intense are the colors? what are their individual values and temperature?

Which sout american country has the highest population density