What is a punnett square? how can it be used to analyze possible genetic outcomes for offspring

A Punnett Square is a square with four, equal-sized inner squares (see attachment) used to determine theoretical probability of offsprings’ genotypes in sexual reproduction.  The two parents’ genotypes are placed one on top and the other to the right of the overall square.  For each inner square, the allele from the parents’ genotypical column and row it’s in are placed into the box.  Dominant (capitalized) alleles come first.  From this, you can analyze each inner square’s listed genotypes — and figure an estimate of diversity of children. For instance, if the condition is recessive in the given document, only two (the hh’s) will be afflicted with it.  (The rest being carriers.)  The upper two (Hh’s) would have a dominant disorder, should this be the gene for that.  So, let’s go with it being recessive.  If one organism with it and one carrying an allele mate, half of there offspring can be predicted to have it, while the other half with be carriers.  Phenotype comes from genotype — if this represented, let’s say, sickle cell anemia (recessive disorder), the children from parents with these genotypes would have a 50% chance of having it.  (The others would have diminished symptoms as opposed to the full-blown version.)  Sorry if I rambled too much.  Let me know if you need clarification on anything.

Its actually d. it can make farmworkers sick