The answer is D: pink heart.

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