Lysosomes a. are the major site of protein synthesis b. maintain a highly alkaline internal environment c. are always used for the cell to "commit suicide" d. contain acid hydrolases that are potentially dangerous to the cell

d. contain acid hydrolases that are potentially dangerous to the cell

Explanation:

Lysosome is an eukaryotic cellular organelle. It maintains an acidic environment and has many hydrolytic enzymes( acid hydrolases). These enzymes are active only inside lysosome because they require acidic environment to function. They are inactive in the alkaline environment of the cell otherwise they would have posed a threat to cell's other components.

When a foreign particle enters the cell, it is engulfed by the lysosome and destroyed. Lysosome is also involved in autophagocytosis where it destroys old or malfunctioning cell components. Resultant amino acids or other components are recycled for cell's use. Sometimes they can be used by cell during apoptosis to destroy itself but it's not always the case.

the sphincter muscles at the end of the digestive tract is the anus.