Different microscopic organisms cause different diseases. when a dangerous microscopic organism is transferred from one person to many people, the disease it carries will spread.

why is this considered a theory instead of a hypothesis or a law?

it is a statement of fact about how nature works instead of an explanation.
it provides an explanation for many observations and accepted hypotheses.
it describes how to test a possible explanation of one specific relationship.
it has not changed over time even though new technology has been developed.

Hi!

The correct answer would be:

It provides an explanation for many observations and accepted hypotheses.

Explanation

A law is a statement of fact that differs from a theory or hypothesis in that it does not provide an explanation for a phenomenon. It does not change over time, and there are no exceptional cases in it. For instance, a day is 24 hours long. It is an obvious, observable fact. There are no explanations, or exceptions - no days where the day is less or more than 24 hours long.

Now, a theory is an explanation of a hypothesis or an observation or phenomenon. A hypothesis is known to be the reason behind a certain observation, and if  the hypothesis survives scrutiny and tests, it is established as a theory - but it may be replaced by better theories or grow obsolete over time, such as the atomic theory which stated that atoms were the smallest indivisible particle in nature.

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day