Final answer:
Lamarck believed that evolution naturally tended toward greater complexity through the Law of Use and Disuse and the Inheritance of Acquired Characteristics.
Step-by-step explanation:
Lamarck believed that evolution naturally tended toward greater complexity. He proposed two ways in which this complexity came about: (1) the Law of Use and Disuse and (2) the Inheritance of Acquired Characteristics. According to Lamarck, the Law of Use and Disuse states that body parts or organs that are used more frequently become stronger and more developed, while those that are not used gradually disappear. Additionally, Lamarck believed that organisms could pass on acquired traits or characteristics to their offspring. For example, if a giraffe stretched its neck to reach leaves higher up in the trees, it would develop a longer neck over time. This longer neck would then be inherited by its offspring.