Which enzymes are secreted only by the pancreas?
nucleases
amylase and proteases
lipases
amylase, proteases, lipases, nucleases

Nucleases are the enzymes that are unique to the pancreas. These are enzymes which break down nucleic acids DNA and RNA into nucleotides. When these nucleotides reach the ileum, they are further degraded or digested into sugars, bases and phosphates. These nucleases are known as DNAase and RNAase

Other pancreatic enzymes such as amylase and protease are also produced by other digestive organs such as the salivary glands and the small intestine respectively. However no other digestive organ has been known to produce nucleases apart from the pancreas.

Nucleases are of two  main types, namely exonucleases which cut off the end of a nucleotide and endonucleases which will cut out certain nucleotide sequences right in the middle of a nucleic acid.

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.

b is the best answer for this question.