B- lack of control.
the scientists did not have a proper control group.
The event in the life of a star that begins its expansion into a giant is its core that was hot enough for fusion reaction.
<h3>What is fusion reaction?</h3>
Nuclear fusion is a type of reaction in which two or more atomic nuclei are fuse to form one or more different atomic nuclei with the release or the absorption of energy.
So we can conclude that the event in the life of a star that begins its expansion into a giant is its core that was hot enough for fusion reaction.
Learn more about reaction here: brainly.com/question/26018275
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Answer:
6.5e-4 m
Explanation:
We need to solve this question using law of conservation of energy
Energy at the bottom of the incline= energy at the point where the block will stop
Therefore, Energy at the bottom of the incline consists of the potential energy stored in spring and gravitational potential energy=
Energy at the point where the block will stop consists of only gravitational potential energy=
Hence from Energy at the bottom of the incline= energy at the point where the block will stop
⇒
⇒
Also 
where 
is the mass of block
is acceleration due to gravity=9.8 m/s
is the difference in height between two positions
⇒
Given m=2100kg
k=22N/cm=2200N/m
x=11cm=0.11 m
∴
⇒
⇒
⇒h=0.0006467m=
<h2>
So, the correct answers are:</h2>
Travels in longitudinal waves
Travels most slowly through a gas
Speeds up when temperature is increased
Is caused by vibration
Explanation for correct answers:
Yes, it does travel in longitudinal waves
Yes, sounds weird, but travels faster in the water
Yes, does speed up when temperature is increased
And yes, Is caused by vibration.
<h2>
Wrong answer is:</h2>
Can travel through a vacuum
Explanation for wrong answer:
actually, in space, there is NO sound, because there are no particals for the sound to vibrate with, there's just empty SPACE.
<span>The three major types of
symbiosis are mutualism, where both species benefit, commensalism, where
one species benefits and the other is unaffected, and parasitism, where
one species benefits and the other is harmed. Symbiotic relationships can occur within an organism's body or outside of it. </span><span>Examples of mutualism include the
relationship between single-celled organisms or animals that incorporate
algae into their bodies. They give the algae necessary nutrients, and
in return receive chemical energy from the photosynthetic algae. Animals
that have this sort of relationship include some sponges, sea anemones
and clams.
Examples of commensalism include remora fish attaching to the bodies
of sharks and eating scraps of food that escape their jaws, and
barnacles living on the jaws of whales with a similar feeding strategy.
Plants have commensal relationships as well, such as many orchids that
grow on taller plants and benefit from the additional sunlight they
obtain, without actually stealing nutrients from the host plant.
Parasitic relationships are many, and parasites include all
disease-causing organisms. This category also includes insects such as
fleas that suck the blood of hosts externally. Parasitism is a very
efficient strategy for organisms, and parasites often lose many of the
features of non-parasitic life forms, instead relying on their hosts for
many of the functions of life.</span>
