2024 AMC 8 Problem 4

When Yunji added all the integers from 1 to 9, she mistakenly left out a number. Her incorrect sum turned out to be a square number. Which number did Yunji leave out?

\textbf{(A)} 5 \qquad \textbf{(B)} 6 \qquad \textbf{(C)} 7 \qquad \textbf{(D)} 8 \qquad \textbf{(E)} 9

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.