The name of the acid present in milk
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lactic acid

The real acidity of milk is due to lactic acid. This is never found in milk when it is first drawn from the udder. It is produced by the action of the lactic acid organisms on the milk sugar. The so-called apparent acidity of milk is what gives fresh milk its acid reaction.

D. learning to structure memories in narrative form
childhood amnesia , also called  infantile amnesia , is the inability of adults to retrieve episodic memories before the age of 2–4 years, as well as the period before age 10 of which adults retain fewer memories than might otherwise be expected given the passage of time