Figure-1 to Figure -4 shows four different spring arrangements . Mass m in each arrangement is displacement from its equilibrium position and released Neglec mass of the springs. Choose the correct statement (s)

Options

A. a. Figure-1 and figure -4 shows springs connected in parallel, effective spring constant `= k_(1), k_(2)`
B. b. Figure-2 and figure -3 show spring connected in series , effective spring constant `= (k_(1)k_(2))/(k_(1)+k_(2))`
C. c. For Figure-1 and Figure -4 frequency of oscillation `= (1)/(2pi)sqrt((k_(1)+k_(2))/(m))` and for figure-2 and figure-3, frequency of oscillation) `= (1)/(2pi) sqrt((k_(1)k_(2))/(m(k_(1)+k_(2))))`
D. d. All of these

Answer

4