The answer is A: 26.

The rule
Each number is the two numbers before it added together. 2 + 2 = 4, 2 + 4 = 6, and so on. The famous Fibonacci sequence works like this, starting 1, 1, 2, 3, 5, 8.
The pattern as Python code
Here is a tiny Python program that follows the same rule. Type it into IDLE and run it to print the whole pattern, including the answer.
a, b = 2, 2
for step in range(7):
print(a)
a, b = b, a + b
When you run it, Python prints:
2 2 4 6 10 16 26
Pixel says: Try changing a number in the code and run it again. Can you make the pattern go on for 20 steps? Meow!