Biological catalysts are protein molecules which 1. speed up a chemical reaction 2. remain unchanged after reaction 3. function optimally at 37 °C 4. do not have an enzymatic activity Select the correct answer using the code given below.

- Biological catalysts are enzymes, which are indeed protein molecules (with a few exceptions like catalytic RNA). - Statement 1 is correct: Enzymes are catalysts, meaning they increase the rate of a chemical reaction without being consumed in the process. - Statement 2 is correct: Like all catalysts, enzymes are not permanently altered or used up during the reaction and can be reused. - Statement 3 is generally correct in the context of human enzymes: Many enzymes in the human body function optimally at physiological temperature, which is around 37 °C. However, the optimal temperature varies greatly among enzymes from different organisms (e.g., enzymes from thermophilic bacteria function at much higher temperatures). Assuming the question refers to typical biological contexts like the human body, this statement is considered correct. - Statement 4 is incorrect: Biological catalysts are enzymes, and their activity is enzymatic activity. This statement directly contradicts the definition. - Based on the statements, 1 and 2 are universally true for catalysts. Statement 3 is true for a common subset of biological catalysts (human enzymes). Statement 4 is false. The option including 1, 2, and 3 is the most fitting choice.