The answer is B: yellow hexagon.

The rule
The pattern repeats every 2 things: yellow circle, yellow hexagon. Then it starts again from the beginning.
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.
pattern = ["yellow circle", "yellow hexagon"]
for position in range(8):
print(position + 1, pattern[position % len(pattern)])
When you run it, Python prints:
1 yellow circle 2 yellow hexagon 3 yellow circle 4 yellow hexagon 5 yellow circle 6 yellow hexagon 7 yellow circle 8 yellow hexagon
Pixel says: Try changing a number in the code and run it again. Can you make the pattern go on for 20 steps? Meow!