The given question is: The pattern of DNA polymorphisms in a single chromosome is called:

Let's look into the options to determine the correct answer with clear reasoning:

1. Monotype: This term generally refers to a single type or form. In genetics, it is not commonly used to describe DNA polymorphisms in chromosomes, hence not the correct term in this context.
2. Genotype: This term denotes the genetic constitution of an individual organism, particularly the alleles that an organism possesses. It refers to the overall genetic makeup rather than specific patterns or sequences of polymorphisms on a single chromosome.
3. Haplotype: This is the correct term. A haplotype refers to a group of genes within an organism that are inherited together from a single parent. It specifically describes the combination of alleles or the set of SNPs (single nucleotide polymorphisms) found in a specific segment of DNA on a single chromosome. It represents the pattern of DNA polymorphisms that are often transmitted together.
4. Phenotype: This is the observable characteristic or trait of an organism. Phenotype results from the interaction of its genotype with the environment. It does not specifically refer to DNA polymorphisms in a chromosome.

Thus, the correct answer is Haplotype, as it accurately describes the pattern of DNA polymorphisms in a single chromosome.

In summary, understanding the definitions of each term and their context in genetics is crucial for distinguishing between them. A haplotype is a region of linked variations in the genome.