To find the next number in the given pattern, we need to observe the given sequence and look for any pattern or rule that governs the numbers. Let's analyze the given sequence step by step:

Step 1: Analyzing the First Set of Numbers
The first set of numbers is: 4, 8, 12

- The difference between the first two numbers is 8 - 4 = 4.
- The difference between the second and third numbers is 12 - 8 = 4.

Based on this observation, we can conclude that the pattern for the first set of numbers is an arithmetic sequence with a common difference of 4.

Step 2: Analyzing the Second Set of Numbers
The second set of numbers is: 16, 20, 24

- The difference between the first two numbers is 20 - 16 = 4.
- The difference between the second and third numbers is 24 - 20 = 4.

Similar to the first set of numbers, the second set also follows an arithmetic sequence with a common difference of 4.

Step 3: Applying the Pattern to Find the Next Number
Since both sets of numbers follow the same pattern, we can assume that the third set of numbers will also follow the same pattern.

- The difference between the first two numbers is 24 - 20 = 4.
- Therefore, the difference between the second and third numbers will also be 4.

To find the next number, we can add 4 to the last number in the second set (24):

24 + 4 = 28

Therefore, the next number in the given pattern is 28.

Final Answer: b) 28