A portal of entry<span> is the site through which micro-organisms enter the susceptible host and cause disease/infection. Infectious agents enter the body through various </span>portals<span>, including the mucous membranes, the skin, the respiratory and the gastrointestinal tracts.</span>
The correct answer is sewage, I just did this stuff in class last week.
The answer is the second choice
An allele is like a trait or a specific gene.
