The correct answer is (a) 25.
The table shows the number of people in each age group who have been vaccinated against COVID-19. The total number of people who have been vaccinated is 100. The number of people in the 18-29 age group who have been vaccinated is 25. Therefore, the value of x in the table is 25.
Option (b), 32, is incorrect because the number of people in the 30-39 age group who have been vaccinated is 32. Option (c), 17, is incorrect because the number of people in the 40-49 age group who have been vaccinated is 17. Option (d), 28, is incorrect because the number of people in the 50-59 age group who have been vaccinated is 28.