Answer:
I want to say it is the middle layer. But not 100% sure. Sorry if its wrong.
The allele for dwarfism - D its dominant
Recessive allele -d
If the person has heterozygous alleles -Dd the person will have achrondroplastic dwarfism
However if the person if homozygous for the allele DD it’s Lethal and person can’t survive
If both parents are Dd
Dd X. Dd
Offspring DD Dd Dd dd
Probability of children who survive with the trait have the genotype Dd
Probability - 1/4 + 1/4
Probability of having surviving children with the trait -1/2 -0.5
Take a dna test... he will be more confident about it then