Final answer:
Avia is likely around 1 year old, as this is the age where children develop the fine motor skills required to stack blocks.
Based on the information provided, Avia's ability to stack two blocks to make a tower suggests that she is likely around two years old (c). At this age, toddlers have developed the fine motor skills needed to build a tower of blocks that is six blocks high. By three years old, they can build a tower nine blocks high.
Step-by-step explanation:
Based on developmental milestones, Avia who has just learned to stack two blocks to make a tower would likely be around 1 year old. During the second year of life, children are developing their motor skills and beginning to explore more complex activities such as walking backward and sideways, as well as climbing stairs with assistance. Fine motor skills are also improving around this age, allowing children to perform tasks like building small block towers.