In 1898 Friedrich Loeffler and Paul Frosch found evidence that the cause of the highly contagious hoof-and-mouth disease in livestock was a microscopic infectious particle. It was discovered that this particle cannot reproduce on its own. Which of these is most likely responsible for causing hoof-and-mouth disease in livestock?

a virus, because it requires a host cell to reproduce

Explanation:

The correct answer would be a virus because a virus is the only microbe that cannot reproduce on its own without a host. A virus utilizes the genetic mechanism of its host to reproduce either lytically or lysogenically.

In lytic cycle, the virus utilizes the genome system of the host to produce more viruses that eventually leave or lyses the host to become independent viral particles, killing the host in the process.

In lysogenic cycle, the virus inserts its genome into that of the host and uses the host's replication machinery to replicate its genome. The virus then waits for the defense mechanism of the host to become weakened before multiplying and lysing the host.

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.