Probability of Inheritance
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In order to determine the percentage of sons having a normal vision when the father has normal vision and the mother is color blind, we need to understand the inheritance patterns of vision and color blindness.

Inheritance of Vision and Color Blindness
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Vision is a complex trait that is influenced by multiple genes. However, for the purpose of this question, we will consider a simplified model where normal vision is dominant and color blindness is recessive.

- Normal Vision: The gene for normal vision is represented by the dominant allele (N).
- Color Blindness: The gene for color blindness is represented by the recessive allele (n).

In this case, the father has normal vision, which means he can have the genotype NN or Nn. The mother is color blind, which means she has the genotype nn.

Punnett Square
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To determine the probability of offspring having normal vision, we can use a Punnett square to visualize the possible combinations of alleles that the children can inherit from their parents.

| N | N
--|---------|-----
n | Nn | Nn

From the Punnett square, we can see that all the possible combinations of alleles for the children will be Nn. None of the combinations will have the recessive allele (n) for color blindness.

Probability Calculation
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Since normal vision is dominant and color blindness is recessive, the genotype Nn represents normal vision. Therefore, the probability of the sons having normal vision is 100%.

Therefore, the correct answer is option 'A' - 0%.