Correct option: A Explanation:The common cold is a viral infection and it can cause by different viruses, such as coronaviruses MERS and SARS. As it is a viral infection so giving antibiotics will not help the patient, as antibiotics are used for the treatment of infection caused by bacteria. Viruses are not living things they are not cells. Viruses are composed of two main components: genetic material can be either DNA or RNA and another is an outer coat of protein called a capsid. Viruses don't have a cell wall, ribosomes, cell membrane, therefore, they are unaffected by antibiotics as antibiotics act on the cell walls, ribosomes, and cell membrane, and some enzymes present in cells of bacteria. Hence, ‘Caused by the virus’ is the correct answer.