Which of the following are true about coliform bacteria?

1.They are used to test water contamination.

2.Coliform bacteria are harmless and cause no disease.

3.They are found naturally in human intestinal tract.

4.Their presence in water is an indication of fecal contamination.

A1 & 4 only

B2 & 3 only

C1, 3 & 4 only

D1, 2, 3 & 4 ✓ Correct

Correct answer: (D) 1, 2, 3 & 4

Explanation

All four points about coliform bacteria hold, from testing contamination to indicating faecal pollution.

Statement 1 is true, as coliforms are used to test water for contamination.

Statement 2 is treated as true here, since coliforms themselves are generally harmless indicators.

Statement 3 is true, because coliforms live naturally in the human intestine.

Statement 4 is true, as their presence in water signals faecal contamination.

Coliforms are easy to detect, which is why they serve as indicator organisms for water safety.

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