25 - A. harder and harder
(We use "harder and harder" for something that increases gradually. "More harder" is incorrect as "harder" is already the comparative form of "hard.")

26 - B. better and better
("Better and better" is the correct form to show improvement over time. "Gooder" is not a standard comparative form of "good.")

27 - B. more and more competitive
("More and more" is used to indicate an increasing trend in something, like competitiveness.)

28 - C. worse and worse
("Worse and worse" is the correct way to show something becoming progressively worse. "More worse" is grammatically incorrect.)

29 - B. better and better
("Better and better" indicates that things are getting increasingly good. "More and more good" is not correct because "good" is an adjective, not a noun.)

30 - A. serious
(In this case, we are using a simple comparative adjective to indicate that the illness became more serious than initially thought.)

31- C. colder and colder
("Colder and colder" is the correct form to show that it becomes progressively colder over time.

32 - B. more and more crowded
("More and more crowded" indicates that the bus became increasingly crowded.)

33 - D. the more
("The more" is the correct structure for expressing a cause and effect relationship between the increase in tasks and the increase in stress.)

34 - A. more and more
("More and more" is used to express something increasing over time, such as the number of young people choosing not to attend college.)

35 - B. the more
("The more" is used here to show that as the price increases, the perceived quality of the product also increases.)