Consider the following statements: 1. When a nerve fibre is stimulated, a profound change is produced in the electrical properties of surface membrane and in steady potential. 2. Upon excitation, the resting potentialis suddenly changed. 3. It is due to sudden and several hundred -fold increase in permeability to Na+ ions. 4. With Na+ ions moving inside the point of stimulation, the positive charge inside the nerve cell increases and reaches a peak called “action potential”. Which of the following statement are correct? (a) 1, 2, 3 (b) 2, 3 (c) 1, 2, 3, 4 (d) 1, 2, 4