 Elicited data is preferred, but still problematic based on the skill level of the speaker, and is not considered naturally occurring speech.The Minimal Trees Hypothesis (MTH) is a highly debated hypothesis which is concerned with the distinction between Functional Categories and Lexical Categories during language transfer.Based on a study of adult SLA learners of German, Korean and Turkish, this hypothesis asserts that only lexical categories transfer from the L1, and functional categories develop over time.