Answer:
B. There are several genes that control the color.
Explanation:
According to the description of the trait in this question in which the plant exhibits a wide range of colors from green to yellow, it shows that the trait for color in such plant is controlled by two or more (several) genes. This kind of inheritance is called a POLYGENIC INHERITANCE.
Polygenic inheritance is a kind of non-mendelian inheritance (does not follow the principles of Mendel) in which phenotypic traits of an organism is controlled by several genes. Each gene possess two alleles, which equally contribute to the phenotypic expression of such trait. Traits controlled by polygenes do not conform to Mendel's laws of inheritance as the offsprings exhibit a range of traits from the mixture of parental traits as stated in the question.
In polygenic inheritance, most of the offsprings exhibit the intermediate phenotype (between green and yellow) with few extremes (green and yellow) due to a combination of the genes in the parental phenotypes. Hence, based on the description in the question, there are several genes that control the color trait in the plant.
