1. a period during which the embryo of a seed is alive but not growing is
dispersal.
fertilization.
germination.
dormancy.

The answer is dormancy

Right away we can tell that dispersal is not the answer. It simply refers to how plant seeds are spread around. 

That leaves us with fertilization, germination, and dormancy. 
Fertilization refers to the union of the male and female reproductive cells which form a fertilized egg. However, the embryo is not alive at this point yet, so we can move on to the next answer choices. 

Germination, this is the actual growth of a seedling from the seed. We are looking for a period in which is not growing so by its very definition, germination cannot be the answer. 

Lastly, we have dormancy. 

Dormancy is a period in which the embryo is dormant. Think about a dormant volcano. There is magma within the volcano, and it is considered "alive" but it does not erupt. Similarly, a dormant embryo of a seed is one that is alive but simply isn't growing. This typically happens during winter. Almost as if it undergoes hibernation. 

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