What best describes how the common cold spreads in the human body?

Viruses replicate inside respiratory cells

Explanation:

The common cold is the most frequent disease that affects the human species and also the most frequent one seen by a Primary Care pediatrician. Since the number of infections is inversely related to age, despite its theoretical banality, it is a problem of the greatest quantitative importance, to which an important percentage of care time is devoted. Children are especially susceptible to this infection, due to the lack of development of immunity to most of the causative viruses, the less development of personal hygiene practices and the greater exposure to etiological agents. The cold is the most frequent diagnosis, both in Primary Care and in emergency services; although, its real frequency is masked by the usual use of synonyms (rhinoadenoiditis, rhinopharyngitis, high-altitude cold, upper respiratory infection) that disperse the diagnosis and may lead to the belief that these are different diseases. We prefer the term “common cold”, both because it is the translation of the most commonly used international nomenclature (“the common cold”), as well as being the name by which the population knows the disease, which has an importance beyond of semantics: most of our patients know very well that the cold has no curative treatment, but this is not the case if we make the diagnosis of “rhinopharyngitis” or “adenoiditis”. The impact of this disease on Public Health is incalculable at first visits, repeated unscheduled controls, truancy and work, and a huge economic impact, in the form of prescriptions, most of the time unnecessary, of antibiotics, cough suppressants, anti-thermics, mucolytics, nasal decongestants and antihistamines. On the other hand, the cold generates a routine of care responsible in good part of the demotivation and professional exhaustion of the pediatrician of AP ("burnout").

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

yes it is weird but true