The answer is B: 47.

The rule
Add 5, then add 10, then 5, then 10, and so on. The pattern of adding takes turns.
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.
adds = [5, 10]
number = 2
for step in range(7):
print(number)
number = number + adds[step % 2]
When you run it, Python prints:
2 7 17 22 32 37 47
Pixel says: Try changing a number in the code and run it again. Can you make the pattern go on for 20 steps? Meow!