Answer:
D) Which types of seeds do our feeder birds eat?
Step-by-step explanation:
A feeder bird is an outdoor object intended to provide food for birds, usually has millet seeds, sunflower, saffron or colza. Because the feeder bird has many different seeds, birds may eat more seeds than one, so some people may be curious about which seeds birds eat the most and which ones eat the least. So, regarding the research Carl and his partner want to start, the most appropriate question to guide scientific research would be "Which types of seeds of our feeder birds eat?"