Answer: The most appropriate statement for research topic in community economy is " The decline in the numbers of bumblebees appeared to be a result of competition for nectar."
Explanation: In ecology, community is defined as group of different species of organism living in same geographical area at a particular time.
The study of the interaction that exists between them is what is called community ecology.
In the above statement, the population of bumblebees is declining because of the activities of other animals or insect who also feed from nectars.