Option D, they are watered more often than tomatoes grown in other gardens, is the right answer.
The improper watering to the tomato plants can lead to several cultivation issues. Watering tomatoes at after drying them out can also lead to tomatoes to swell suddenly and splitting the peel of the tomatoes which permits fungal germination to take hold causing the complete ruin of the fruit. Therefore, it may noticed that watering plays an important role in the cultivation of tomatoes. It is clear, therefore, that the reason behind the juiciest tomatoes is the watering; the Botanist watered tomatoes plants of his garden more than they were watered in other gardens.
The horse and donkey, though closely related by sharing a common ancestor, are different species. They have different number of chromosomes hence pairing of homologous chromosomes during fusion of gametes becomes complicated. The mule will have an extra chromosome from the horse hence will have abnormalities such as sterility. A Mule is unable to reproduce due to this same phenomenon. Homologous chromosomes are not well paired for meiosis I.