Darwin's theory of evolution is based on the principle of

Step 1: Analyze the question The question asks what principle Darwin's theory of evolution is built on.

Step 2: Explain the concept Charles Darwin, in On the Origin of Species (1859), proposed that species change over time through natural selection, often summarized as "survival of the fittest." Its main points are:

1. Variation: Individuals in a population differ in their traits.
2. Overproduction: Organisms produce more offspring than can survive.
3. Struggle for existence: Offspring compete for limited resources such as food, space and mates.
4. Survival of the fittest: Individuals with traits better suited to the environment survive and reproduce more.
5. Inheritance: Favourable traits are passed on to the next generation, so the population gradually changes over time.

Step 3: Check each option

• A. Use and disuse of organs: This belongs to Lamarck, who said organs that are used become stronger and those not used weaken.
• B. Natural selection: This is the central principle of Darwin's theory.
• C. Acquired characteristics: Also Lamarck's idea, that traits gained during an organism's life are inherited. It has been disproved.
• D. Mutation: This is a source of variation, and it was explained later by geneticists. Darwin did not base his theory on it, because he did not know about genes.

Step 4: Answer The correct option is B. natural selection.

Exam tip: Remember the pairing: Darwin = Natural selection and Lamarck = Use and disuse / Acquired characteristics. Whenever JAMB lists both names or ideas together, separate them this way. Think of the Lamarck giraffe stretching its neck, whose long neck is then passed on, versus Darwin's giraffes where the naturally long-necked ones survive.