Which of the following is non-steroidal hormone?

Explanation

Insulin is a non-steroidal hormone, distinct from steroid hormones which are derived from cholesterol and are fat-soluble. Instead, insulin is a protein hormone, water-soluble, and functions by binding to receptors on the cell membrane to exert its effects. In contrast, cortisol, testosterone, and aldosterone are steroid hormones, characterized by their ability to pass through cell membranes and interact with receptors inside the cell. These differences in solubility and receptor interaction are key to distinguishing between steroidal and non-steroidal hormones, confirming that Insulin is the correct answer.