Philology means study of:

Languages

The answer is Option 2: Languages.

Philology is the study of language and especially of its historical development. It is a broad field that encompasses the study of linguistics, literary criticism, textual criticism, and history. Philologists study how languages change over time, how they are used in different contexts, and how they relate to each other. They also study the history of literature and the interpretation of texts.

Option 1: Plants is the study of botany. Option 3: Philosophy is the study of knowledge, reality, and existence. Option 4: Life processes is the study of biology.