)a vaccine that fits the first general rule on immunization "the more similar a vaccine is to the natural disease, the better the immune response to the vaccine" is

The correct answer in the given statement above in a way of completing it is the MMR. The MMR vaccine is a vaccine used for immunization in means of fighting certain diseases such as rubella, mumps and even measles in which is being administered by injection.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.

a covalent bond, specfically triple bond