The answer is C: pink circle.

The rule
The pattern repeats every 4 things: pink circle, pink circle, green heart, purple star. 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 = ["pink circle", "pink circle", "green heart", "purple star"]
for position in range(10):
print(position + 1, pattern[position % len(pattern)])
When you run it, Python prints:
1 pink circle 2 pink circle 3 green heart 4 purple star 5 pink circle 6 pink circle 7 green heart 8 purple star 9 pink circle 10 pink circle
Pixel says: Try changing a number in the code and run it again. Can you make the pattern go on for 20 steps? Meow!