Which of the following causes the denaturation of protein?

All of these

The answer is (4) all of these.

Denaturation of protein is the loss of the native structure of a protein. This can be caused by a number of factors, including:

• Heat: Heat can disrupt the hydrogen bonds and other interactions that stabilize the native structure of a protein.
• Change in pH: The pH of a solution can affect the ionization of amino acids in a protein, which can disrupt the electrostatic interactions that stabilize the native structure.
• Addition of detergents or urea: Detergents and urea are chaotropic agents, which means that they disrupt the hydrophobic interactions that stabilize the native structure of a protein.

Therefore, all of the options listed in the question can cause denaturation of protein.

Here are some additional details about denaturation of proteins:

• Denatured proteins are typically less soluble and less active than native proteins.
• Denatured proteins can sometimes be renatured, but this is not always possible.
• Denaturation of proteins can be a reversible or irreversible process.