E. coli is commonly found in the intestines of warm-blooded animals, including humans, and is often used as an indicator of fecal contamination in water. The presence of E. coli in water indicates the potential presence of fecal matter and the possible presence of harmful pathogens associated with fecal contamination. It is an important marker for assessing water quality and safety.
So, the correct option is (B): Faecal matter