Because every strand much be different then the other ones or the same but different DNA
by injecting the weakened virus into your body it helps the body familiarize and create the right antiviruses for the virus so that if it ever gets in your system you can actually fight it.
hope that helps <3
Urbanization has changed literally everything over the years from the environment being destroyed little by little but also it effects water pollution and by factories being made puts a bunch of terrible greenhouse gasses that are not healthy to breath in.
mark this as best if helps
The answer to your rather difficult question is paper. only certain trees make gum rubber, only certain trees make syrup and none of them make turpentine( an extremely flammable substance. the only thing you can get from almost every tree is paper.
The answer is b because genes can control sn organisms traits
