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.

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals

answer; they are called (pebbling);