Norrish-Smith effect or Trommsdorff effect during free radical bulk polymerization at high conversion is characterized by $\_\_\_\_$.
- increase in rate of polymerization with time due to increase in viscosity
- decrease in rate of polymerization with time due to increase in viscosity
- decrease in rate of polymerization with time due to reduction in viscosity
- increase in rate of polymerization with time due to reduction in viscosity