Let z1=1+iz_1 = 1 + iz1=1+i and z2=1−iz_2 = 1 - iz2=1−i. Which of the following statements about their product z1⋅z2z_1 \cdot z_2z1⋅z2 is true?
The product is a purely imaginary number.
The product is equal to 000.
The product is a real number.
The product has a modulus of 111.