I think its if one parent has no alleles for the disease.
The probability is 1/16 that a gamete will receive only paternal chromosomes. In life
cycles that alternate between haploid and diploid stages, fertilization doubles
the number of chromosomes per cell, The pairing of chromosomes along
their lengths , which is essential for crossing over is referred to as synapsis
Answer : Option B) Cell theory has been unchanged for many decades and as a result can be accepted as fact.
Explanation : As cells are basic units of life and all the living beings are made up of cells, this was correctly defined by the cell theory. This theory is since its discovery not changed for many decades and is widely accepted as a fact too.