Final answer:
Apache Pig is the Hadoop application that provides a high-level programming language for data transformation on unstructured data, allowing for complex transformations without deep Java knowledge.
Step-by-step explanation:
The Apache Hadoop application that provides a high-level programming language for data transformation on unstructured data is D. Pig. Apache Pig allows for the analysis of large data sets by using a scripting language known as Pig Latin, which is designed to handle all kinds of data, especially unstructured data. Pig enables data workers to write complex data transformations without having to know Java, the underlying language that powers most of Hadoop's ecosystem.
Apache Hive is another data warehouse infrastructure built on top of Hadoop, but unlike Pig, it provides a SQL-like language, which can be more familiar to users with a background in SQL but less flexible when it comes to unstructured data.
Sqoop is a tool designed to transfer data between Hadoop and relational databases or mainframes, and Zookeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services.