Baby Rebecca is putting her hands by her face. She accidentally puts her thumb in her mouth. She reflexively begins to suck on her thumb. Later in the day, she tries to put her thumb back into her mouth, and the assumption is that she enjoyed sucking her thumb earlier and is trying to repeat the action. Which sensorimotor substage is Rebecca in?

First habits and primary circular reaction

Explanation:

First habits are the initial habits that a child learns between the range of one-month to four month old.Primary circular reaction are the responses that accidentally occur and baby tends to repeat those movement according to their ability.E.g.- sucking thumb in mouth etc.

According to the question ,Rebecca is displaying primary circular reaction as initial habit that she gained accidentally by putting her thumbs in her mouth for sucking it and thus, repeats the action due to enjoyment.

well this isn't a question but if you are asking if it is true or false it is, true.