Lamarck's theory of evolution is based on the fact that

Step 1: Analyze the question The question asks for the main idea behind Lamarck's theory of evolution.

Step 2: Explain the concept Jean-Baptiste Lamarck (1744-1829) proposed the theory of inheritance of acquired characters. It rests on two main ideas:

1. Use and disuse: Organs that are used often become stronger and larger. Organs that are not used weaken and may disappear.
2. Inheritance of acquired characters: Features an organism develops during its lifetime are passed on to its offspring.

Classic example: The giraffe. Ancestors stretched their necks to reach high leaves. The stretched necks were then passed on to their young, so over generations giraffes developed long necks.

Step 3: Evaluate the options

• A. Organisms acquire genes from their parents. This is simply heredity. Lamarck did not base his theory on genes, which were not understood in his time.
• B. Organisms pass on acquired characters to their offspring. This matches Lamarck's theory exactly.
• C. Characteristics are determined by the creator. This is the idea of special creation, not Lamarck's theory.
• D. Characteristics are the sum of their parents' characters. This describes blending inheritance, not Lamarckism.

Step 4: Answer

Tip: Link Lamarck with "Acquired", and Darwin with "Natural Selection". If you see "acquired characters" in an option about evolution, it points to Lamarck. Remember that modern genetics has shown acquired characters are generally not inherited, which is why Lamarck's theory was rejected. WASSCE still asks about it often, so keep the giraffe example in mind.