Select the correctly constructed CHECK constraint to validate the signup_date column of type data, to ensure that values placed into it are between 2020-01-01 and 2025-01-01.
a.) CHECK (signup_date BETWEEN 2020-01-01 AND 2025-01-01)
b.) CHECK (signup_date IN '2020-01-01' AND '2025-01-01')
c.) CHECK (signup_date BETWEEN '2020-01-01' AND '2025-01-01')
d.) CHECK (signup_date BETWEEN '2020-01-01' OR '2025-01-01')