Two important cognitive development milestones of sensorimotor stage of Piaget’s theory of cognitive development are :

The correct answer is Object permanence and deferred imitation.

In Jean Piaget’s theory of cognitive development, the sensorimotor stage is the first stage, spanning from birth to approximately 2 years of age. During this period, infants construct an understanding of the world by coordinating sensory experiences (such as seeing and hearing) with physical motor actions.

Two major cognitive milestones achieved during the sensorimotor stage include:

1. Object Permanence: This is the understanding that objects continue to exist even when they cannot be seen, heard, or touched. Infants typically begin to develop this milestone around 8 to 12 months of age.

2. Deferred Imitation: This is the ability to observe an action or behavior and repeat/imitate it at a later time (after a delay), demonstrating that the infant has developed mental representation abilities.

Analysis of other options:

- Animism and Transformation: Associated primarily with the pre-operational stage (around 2 to 7 years).
- Classification and Seriation: Associated with the concrete operational stage (around 7 to 11 years).
- Reversibility of thought and hypothetic-deductive reasoning: Reversibility develops in concrete operations, while hypothetic-deductive reasoning is characteristic of the formal operational stage (11+ years).