Can someone HELPPP What is the meaning of the idiom “on top of the world”?

sad and lonely
surprised and cheerful
ecstatic and confident
arrogant and intelligent

Read the claim. human bodies have developed over time to support a vegetarian diet. which sentence provides the best supporting evidence for the claim? because humans have evolved over millions of years, it makes sense that our diet has evolved as well. i can feel the negative effects of meat and its excess vitamins when i consume meat products. the length of human intestines is better suited to digest food derived from plants than to digest meat. human taste buds have matured throughout history in a way that makes people crave the flavor of meat.