Mendel's experiments on pea plants focused on the study of characteristics that could be measured and counted, which he classified as quantitative characters. However, he also took into account how these characters related to each other, considering both their quantity and quality. Hence, option C is the correct answer.

Explanation:

Mendel's experiments involved the observation of pea plants with distinct characteristics, such as seed color, flower color, and pod shape. He noticed that these traits were inherited from one generation to the next, following specific patterns. By crossing plants with different traits, he was able to determine the rules of inheritance that govern the transmission of genetic information.

Quantitative characters:

Mendel's experiments primarily focused on traits that could be quantified, such as the ratio of dominant to recessive alleles in the offspring. He counted the number of plants that exhibited a particular trait and compared it to the expected ratio based on his hypothesis. For example, he found that when he crossed two pea plants that differed in seed color (yellow and green), the resulting offspring had a 3:1 ratio of yellow to green seeds.

Quantity in relation to quality:

However, Mendel also recognized that these quantitative characters were related to qualitative characters. For instance, he observed that the color of a pea plant's flower was related to the color of its seeds. By studying the relationship between these traits, he came up with a more comprehensive theory of inheritance that took into account both the quantity and quality of traits.

Quality as well as quantity:

While Mendel's experiments primarily focused on quantitative characters, he did not ignore qualitative characters entirely. In fact, he used them to explain why certain traits were dominant over others. For example, he found that the trait for yellow seed color was dominant over the trait for green seed color, which he attributed to the presence of a dominant allele that produced yellow pigments.

Conclusion:

In summary, Mendel's experiments on pea plants considered both quantitative and qualitative characters, as well as the relationship between them. He used his observations to formulate the laws of inheritance that still form the basis of modern genetics.