Answer:
c. environmental factors such as soil pH
Explanation:
Some traits are controlled by both genetics and environment. Two twins with identical genetic makeup will also have different traits due to exposure to different environment.
Hydrangea is one of the plants on which environment has major effect. It has blue flowers in acidic soil and pink flowers in alkaline soil. Hence soil pH affects the colour of Hydrangea flowers. Plants with same genotype can also produce different coloured flowers due to difference in surrounding environment. Since it has been given that all the planted flowers had same genotype, existance of multiple alleles or the relationship between the alleles have no effect on the difference in colour of flowers.
