Final answer:
The hollow cone nozzle is ideal for complete leaf surface coverage because it produces a fine, uniform spray that ensures effective treatment of plants. Other nozzle types serve different purposes and are not as suited for thorough coverage as the hollow cone nozzle.
Step-by-step explanation:
The type of nozzle that is well-suited for times when complete coverage of the leaf surface is critical is a b. Hollow cone nozzle. This nozzle type produces a fine spray pattern that can cover leaves evenly, which is essential in applications like pesticide or herbicide delivery where contact with the entire surface is necessary for effective treatment. The hollow cone nozzle creates droplets that are smaller and more uniform than those produced by other types, promoting thorough coverage.
Other nozzle types such as the flat fan nozzle, solid stream nozzle, and variable rate nozzle are used for different purposes. For instance, a. Flat fan nozzle is typically used for even coverage over a broad area, c. Solid stream nozzle for direct applications with minimal drift, and d. Variable rate nozzle for precision application where rates can be adjusted according to specific conditions.