The answer is A: teal circle.

The rule
The pattern repeats every 2 things: green heart, teal circle. 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 = ["green heart", "teal circle"]
for position in range(8):
print(position + 1, pattern[position % len(pattern)])
When you run it, Python prints:
1 green heart 2 teal circle 3 green heart 4 teal circle 5 green heart 6 teal circle 7 green heart 8 teal 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!