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 student ( stuid number, lname text, fname text, age number, sex text, major number, advisor number, city_code text )
TABLE: CREATE TABLE faculty_participates_in ( facid number, actid number )
TABLE: CREATE TABLE participates_in ( stuid number, actid number )
TABLE: CREATE TABLE activity ( actid number, activity_name text )
TABLE: CREATE TABLE faculty ( facid number, lname text, fname text, rank text, sex text, phone number, room text, building text )

### Question ###
Find the number of activities available.

### Accurate SQL ###

SELECT COUNT(*) FROM activity