Translate the following question to SQL: Which poll resource provided the most number of candidate information?

Schema: CREATE TABLE candidate (
    Candidate_ID INT   PRIMARY KEY,
    People_ID INT,
    Poll_Source TEXT,
    Date TEXT,
    Support_rate REAL,
    Consider_rate REAL,
    Oppose_rate REAL,
    Unsure_rate REAL,
    UNIQUE (Candidate_ID),
    FOREIGN KEY (People_ID) REFERENCES people(People_ID)
);

CREATE TABLE people (
    People_ID INT   PRIMARY KEY,
    Sex TEXT,
    Name TEXT,
    Date_of_Birth TEXT,
    Height REAL,
    Weight REAL,
    UNIQUE (People_ID)
);
user
SELECT poll_source FROM candidate GROUP BY poll_source ORDER BY count(*) DESC LIMIT 1
assistant