The correct answer is option 1: Vector. Insects that transmit diseases are called vectors. Vectors are organisms that carry and transmit pathogens (such as viruses, bacteria, or parasites) from one host to another. Mosquitoes, ticks, fleas, and some flies are examples of vectors that can spread diseases such as malaria, dengue fever, Lyme disease, and Zika virus. Vectors play a crucial role in the transmission of these diseases by carrying the pathogens and introducing them into a host`s bloodstream. It is important to control and prevent vector-borne diseases through measures such as using insect repellents, wearing protective clothing, and eliminating breeding sites for mosquitoes and ticks.