The bottom of page 92 of the article mentions early synthetic surfactants polymers that were made from propylene monomers.

The bottom of page 92 of the article mentions early synthetic surfactants polymers that were made from propylene monomers.  This is the sodium alkylbenzenesulfate (ABS) detergent mentioned in the textbook.  Take a look at the structure in figure 15-7.  How many propylene monomers were incorporated into that polymer?  Explain