Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE department ( dept_name VARCHAR, dept_code VARCHAR )
TABLE: CREATE TABLE course ( dept_code VARCHAR, crs_code VARCHAR, crs_credit INTEGER )
TABLE: CREATE TABLE CLASS ( crs_code VARCHAR )

### Question ###
Find the name of the department that offers the largest number of credits of all classes.

### Accurate SQL ###

SELECT T3.dept_name FROM course AS T1 JOIN CLASS AS T2 ON T1.crs_code = T2.crs_code JOIN department AS T3 ON T1.dept_code = T3.dept_code GROUP BY T1.dept_code ORDER BY SUM(T1.crs_credit) DESC LIMIT 1