The laboratory tests on a soil sample yields the following results: natural moisture content $=18 \%$, liquid limit $=60 \%$, plastic limit $=25 \%$, percentage of clay sized fraction $=25\%$. The liquidity index and activity (as per the expression proposed by Skempton) of the soil, respectively, are
- $-0.2$ and $1.4$
- $0.2$ and $1.4$
- $-1.2$ and $0.714$
- $1.2$ and $0.714$
