Please list the titles of all the films under the category of "Horror" and has a rental rate of $2.99.
"Horror" is the name of category; rental rate of $2.99 refers to rental_rate = 2.99
SELECT T1.title FROM film AS T1 INNER JOIN film_category AS T2 ON T1.film_id = T2.film_id INNER JOIN category AS T3 ON T2.category_id = T3.category_id WHERE T3.name = 'Horror' AND T1.rental_rate = 2.99