Final answer:
The pease porridge in the nursery rhyme is nine days old, as indicated by the lyrics of 'Pease Porridge Hot'.
Step-by-step explanation:
The nursery rhyme in question refers to 'pease porridge' being in the pot for nine days old. The correct answer to the question, 'How many days old was the pease porridge in the pot?' is B) Nine days old. This is based on the line from the classic nursery rhyme "Pease Porridge Hot", which includes the lyrics, 'Pease porridge hot, pease porridge cold, Pease porridge in the pot, nine days old.' It's important to note that nursery rhymes are often not meant to be interpreted literally, but for the purpose of this question, the answer reflects the information given in the rhyme.