Which statement best describes the concept of tropism?
a) Inanimate objects such as food and water can transmit microbes from one source to another when the new host is immunosuppressed, whereas animate vectors can pass microbes to robust, healthy individuals.
b) Transmission of viruses can only occur from animate reservoirs, whereas bacteria can be transmitted from either inanimate or animate reservoirs to a new host.
c) SARS-CoV-2 binds to a number of human cell types via the ACE2 receptor whereas rhinovirus binds only to the epithelium in the upper respiratory tract.
d) Pregnant females can transmit pathogens only to their unborn child, whereas indirect transmission to other individuals can occur in any infected person.