Answer:
Seven segments
Explanation:
As given in the question -  
After every  twenty microseconds one reaction occurs i.e breakdown of polysaccharides.  
This means that after every  twenty microseconds the polysaccharides is broken down  
The total time for this hydrolysis reaction is   micro seconds
 micro seconds
Thus , there will be six phases of division each after every  twenty microseconds
After 1st  twenty microseconds , total segments is equal to two
After 2nd  twenty microseconds , total segments is equal to three
After 3rd  twenty microseconds , total segments is equal to four
After 4th twenty  microseconds , total segments is equal to five
After 5th twenty  microseconds , total segments is equal to six
After 6th twenty microseconds , total segments is equal to seven