The common cold is caused by which of the following?

$A$ doctor identifies symptoms of nasal congestion,headache,sore throat,hoarseness,and cough in a patient. The conclusion is that the patient is infected by which pathogen?

The aphid $Acyrthosiphon$ transmits which of the following causal agents?

Which of the following diseases is caused by the smallest virus?

Dengue is transmitted by

For which of the following diseases has a definitive vaccine not yet been developed?