The answer is A: Collagen
Vestigial structures are taken as an example of evolution because they give us an indication of structures that, due to the adaptation to the environment, disappeared.
At the end of the vertebral column, we have the coccyx as an example of this. Its believed that it could have formed a tail and currently, is only a small bone without any specific function, even some individuals are born without it.
B. Independent meaning by itself. Dependent meaning together, or not by itself, and since both are going 60mph and they both stop it’s dependent because they’re depending on each other to stop.
Three factors that determine the reactivity of elements are the
valence electrons are the electrons in the outermost electron shell of an atom.
The number of electrons in an atom's outermost valence shell governs its
bonding behaviour. That is why in periodic table the elements were put together
according to their numbers of valence electrons.
METALS
The most reactive kind of metallic element is a metal from
Group 1 sodium or potassium.
An atom in Group 1 has only one valence electron.
NON-METALS
A nonmetal tends to attract another valence electrons to
attain a full valence shell.