What does Gdp measure, and what are the four components of gdp?​

According to this one article...

"The four components of gross domestic product are personal consumption, business investment, government spending, and net exports. 1  That tells you what a country is good at producing. GDP is the country's total economic output for each year. It's equivalent to what is being spent in that economy."

its c not d   tell me if that´s correct