Which of the following is included in the definition of agricultural use?

The definition of agricultural use encompasses activities directly related to the cultivation of crops and the management of agricultural environments. In this context, using pesticides for the regulation of plant growth falls firmly within the realm of agricultural practices. This includes actions like using herbicides to control weeds, fungicides to prevent diseases, and plant growth regulators to enhance crop productivity.

This option reflects practices typically found in farming and agricultural management, which are concerned with ensuring healthy plant development and maximizing agricultural yields. The agricultural use of pesticides is heavily regulated to promote safety for the environment, humans, and animals while supporting crop production.

The other options do not align with the definition of agricultural use in the same way. Selling pesticides in labeled packages for home use relates to consumer markets rather than agricultural production, while use by structural pest control operators typically pertains to urban pest management rather than farming practices. Additionally, use exclusively under veterinarian prescriptions is primarily focused on animal health rather than farming activities. Thus, the correct choice accurately reflects the intended agricultural context.