Answer:
The sentence that best summarizes the main idea of the first paragraph in this passage is "Mosquitos are annoying, but can also cause damage by spreading disease."
Explanation:
The question is not complete since it does not provide the reference paragraph, here is the paragraph:
Almost everyone has had the unpleasant experience of being bitten by a mosquito. Mosquito bites can cause severe skin irritation due to an allergic reaction to the mosquito's saliva; this is what causes the red bump and itching. But transmission of certain serious diseases, such as malaria, dengue fever and several forms of encephalitis, including West Nile virus, are a more serious consequence of some mosquito bites. Other animals, such as dogs and horses, are highly susceptible to mosquito-borne diseases, such as heartworms, eastern equine encephalitis and West Nile Virus.
This paragraph presents as the main idea the danger that mosquitos carry with them as they can infect others with deathly diseases, some kinds are mention like malaria, and dengue fever, the second part of the paragraph give extra information about how other species can also be affected by this insect but as a supporting detail, the main idea makes references to the spread of diseases.