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 Participates_in (actID VARCHAR)
TABLE: CREATE TABLE Activity (activity_name VARCHAR, actID VARCHAR)

### Question ###
What is the name of the activity with the most students?

### Accurate SQL ###

SELECT T1.activity_name FROM Activity AS T1 JOIN Participates_in AS T2 ON T1.actID = T2.actID GROUP BY T1.actID ORDER BY COUNT(*) DESC LIMIT 1