Need help on part 2 pls leave some answer

The correct answer would be -

Punnett square is given below and on the base of the result of Punnett square, Millie should mate with Denver to get three different colors of puppies.

Explanation:

The question says that Millie has a genotype BB*, which is a combination or heterozygous condition of dark brown allele B and white allele B*, now cross with Denver (light brown color):

Cross 1:

         B      B*

 B    BB   BB*

  B*  BB* B*B*

the results is : 25% dark brown, 50% light brown and 25% white.

cross 2: with Charley (white color)

    B     B*

B* BB*  B*B*

B* BB*  B*B*

there is only white and light brown puppies produced

Thus, the correct answer is - Denver.

d. sodium chloride ions.