Solve cos²t + cos2t + 1=0. Statements:
1. The equation 3cos²t = 0 may be used to solve the equation.
2. The equation cos²t + 2cost + 1 = 0 may be used to solve the equation.
3. t = π/2 + πk, where k = 0, ±1, ±2, ±3.
4. t = π + 2πk, where k = 0, ±1, ±2, ±3.
a. 1 & 3 only.
b. 2 & 4 only.
c. 2 & 3 & 4 only
d. All statements are correct.