In a database, a rule is defined as $(\mathrm{P} 1$ and $\mathrm{P} 2)$ or $\mathrm{P} 3$ ? $\mathrm{R} 1(0.8)$ and $\mathrm{R} 2(0.3)$, where $\mathrm{P} 1$, $\mathrm{P} 2$. $\mathrm{P}3$ are premises and $\mathrm{R} 1$. $\mathrm{R} 2$ are conclusions of rules with certainty factors ($\mathrm{CF} $) $0.8$ and $0.3$ respectively. If any running program has produced $\mathrm{P} 1$, $\mathrm{P} 2$, $\mathrm{P} 3$ with $\mathrm{CF}$ as $0.5,0.8$, $0.2$ respectively. find the $\mathrm{CF}$ of results on the basis of premises.
- $\mathrm{CF}(\mathrm{R} 1=0.8), \mathrm{CF}(\mathrm{R} 2=0.3)$
- $\mathrm{CF}(\mathrm{R} 1=0.40), \mathrm{CF}(\mathrm{R} 2=0.15)$
- $\mathrm{CF}(\mathrm{R} 1=0.15), \mathrm{CF}(\mathrm{R} 2=0.35)$
- $\mathrm{CF}(\mathrm{R} 1=0.8), \mathrm{CF}(\mathrm{R} 2=0.35)$
