To solve this problem, we need to determine the number of days it takes for the snail to reach the top of the pit.
Each day, the snail climbs 5 meters upwards. However, at night it slides 4 meters back downwards. Therefore, the snail makes a net progress of 1 meter each day (5 meters climbed - 4 meters slid back).
To reach the top of the pit, the snail needs to climb a total of 20 meters. Since it makes a net progress of 1 meter each day, it will take the snail 20 days to reach the top of the pit.
Let's go through each option to determine the correct answer:
Option A) 12 days - This option is incorrect because it is less than the total number of days required for the snail to reach the top of the pit.
Option B) 9 days - This option is incorrect because it is less than the total number of days required for the snail to reach the top of the pit.
Option C) 16 days - This option is correct because it is equal to the total number of days required for the snail to reach the top of the pit.
Option D) 2 days - This option is incorrect because it is less than the total number of days required for the snail to reach the top of the pit.
The correct answer is C) 16 days. This option is correct because it represents the total number of days required for the snail to reach the top of the pit.