Help me with the Trihybrid Cross using the Punnett Square?

Marco' genotype:-
CcDdSs
As Noreen's both parents are have recessive alleles, so they will only give their recessive alleles to Noreen.
So, Noreen's Genotype:-
ccddss.

Marco's Gametes- CDS, CDs, CdS,Cds,cDS,cDs,cdS,cds,
While Noreen's gametes are:- cds.


Now, you do a punnet square.

You will get
CcDdSs-8
CcDdss-8
CcddSs-8
Ccddss-8
ccDdSs-8
ccDdss-8
ccddSs-8
ccddss-8.

So, the Genotypic ratio is 1:1:1:1:1:1:1:1
And phenotypic Ratio is also 1:1:1:1:1:1:1:1

Marco produces gametes with every combination of C or c, D or d, and S or s.

Remember that in a monohybrid cross the heterozygote produces two possible gametes, and in a dihybrid cross he produces four. The number doubles with each additional gene, so for a trihybrid there are 8 possible gametes.
(why does it double? Because each combination of C/c and D/d alleles can be paired with either S or s).

Here's one way to list them systematically:
CDS
CDs
CdS
Cds
cDS
cDs
cdS
cds
(note that I've listed the four dihybrid gametes CD, Cd, cD, and cd, then added S or s to each. To add a fourth gene A you would take each of these and add A or a.)

Meanwhile, Noreen is homozygous for all the recessive alleles, so all of her gametes are the same.
The Punnett Square is 8x1