Answer:
The third and the fourth option.
![3Mg+1Fe_2O_3 \\ = 3MgO + 2Fe[tex]3Mg+1Fe_2O_3 \\ = 3MgO + 2Fe \\](https://tex.z-dn.net/?f=3Mg%2B1Fe_2O_3%20%5C%5C%20%20%3D%203MgO%20%2B%202Fe%3C%2Fstrong%3E%3C%2Fp%3E%3Cp%3E%3Cstrong%3E%5Btex%5D3Mg%2B1Fe_2O_3%20%5C%5C%20%20%3D%203MgO%20%2B%202Fe%20%5C%5C%20)

Explanation:
The number of products and reactants are balanced
Answer:
genes
Explanation:
the puppy got half their mother's chromosomes and half their dad's chromosomes therefore inheriting parts of their genes
The answer is <em>A.) You have antibodies that already recognize the virus</em>
Viruses and diseases are always changing. When we get sick with say the flu, a virus, or the cold of sorts, our body attacks it until it fights off the disease. You can't get sick from the same strand of sickness because once your body defeats the virus, it knows how to protect the body from it because of the antibodies, so the virus ends up evolving to get past your immune system again.
I hope this helped! Have a wonderful day :)