Correct Answer - B

Here, `h_(T)=20m,R=6.4xx10^(6)m=64xx10^(5)m`

If the anteena is at ground level

Range, `d=sqrt(2h_(T)R)=sqrt(2xx20xx(64xx10^(5)))`

`=16xx10^(3)m=16km `

Area covered, `A=pid^(2)=(22)/(7)xx(!6)^(2)=804.6km^(2)`

If the receiving antenna at a height of 25m.

Range `d_(1)=sqrt(2h_(T)R)_sqrt(2h_(R)R)`

`=sqrt(2xx20xx(64xx10^(5)))+sqrt(2xx25xx64xx10^(5))`

`=16xx10^(3)+17.9xx10^(3)=33.9xx10^(3)m=33. 9km`

Area covered `A_(1)=pid_(1)^(2)=(22)/(7)xx(33.9)^(2)=3611.8km^(2)`.

percentage increase in area `=(A_(1)-A)/(A)xx100`

`=((3611.8-804.6)/(804.6))xx100=348. 9%`