D. All of the above are true.
<span>he eyes and love are connected. ... The darkened environment also allows our pupils to dilate which can be a subconscious signal of stimulation, attraction and readiness for love. Studies have shown that our pupils dilate wider than normal when we are excited about something and even someone.</span>
The source is the allele for beak size being different, or more specifically the DNA sequences being different.
Answer:
A, B, AB, O are the possibilities.