In child development, certain established patterns guide the growth and development process. One of the fundamental concepts is that the growth and development process in children is both continuous and orderly. Let's explore what this means and why it is considered correct:

1. Continuous: Growth and development in children occur over a period and continue throughout childhood and adolescence. This continuity ensures that development is a gradual process without abrupt stops, aligning with the biological and psychological progression that starts from conception and continues through adulthood.
2. Orderly: This refers to the predictable sequence of developmental milestones that children typically achieve as they grow. For instance, babies generally learn to grasp objects before they learn to walk. This orderly progression is crucial for the study of developmental psychology as it helps in understanding typical developmental stages.

Let's evaluate the provided options against this understanding:

• Irregular and unpredictable: This is incorrect as it suggests no consistent pattern, which contradicts the established developmental milestones observed universally.
• Continuous and orderly: This is the correct choice as it accurately describes the predictable and progressive nature of child development.
• Continuous and accidental: This is incorrect because while development is continuous, it is not accidental but a result of both genetic and environmental interactions.
• Based on hereditary effect only: While heredity plays a role, development also depends significantly on environmental factors, making this option insufficient on its own.

In conclusion, the correct pattern described in child development is continuous and orderly, as it aptly captures the essence of how children naturally grow and develop over time.