To answer the following question(s), refer to the Mandelbrot replacement process described by:
∙ Start: Choose an arbitrary complex number s, called the seed of the Mandelbrot sequence. Set the seed s to be the initial term of the sequence 
∙ Procedure M: To find the next term in the sequence, square the preceding term and add the seed 
Suppose that at a certain step, the Mandelbrot replacement process produces the value

and at the next step it produces the value

Then the seed s equals
◦

.
◦ 2.
◦ 21.
◦ 1.
◦ none of these