Which of these conditions are always true of populations evolving due to natural selection? Condition 1: The population must vary in traits that are heritable. Condition 2: Some heritable traits must increase reproductive success. Condition 3: Individuals pass on most traits that they acquire during their lifetime. a. Condition 1 only b. Condition 2 only c. Conditions 1 and 2 d. Conditions 2 and 3