Answer: B) 9 Explanation:   Here in 2nd column if you add the individual digits  we get  3 + 7 + 0 =10 , 2 + 2 + 4 = 8 , 7 + 3 + 0 = 10   7   10   3  --> 7+3 =10   6   8     2  --> 6+2 =8   x   10   1  --> x+1 =10   Here we can observe that by adding 1st and 3rd column elements we get 2nd column elements  --> x = 9

Answer: A) flowing rivers Explanation: A karst topography is that which composes of limestone and its associated features and structures. Karst topography and caves develop in limestone rocks due to their solubility in dilute acidic groundwater. The solubility of limestone in water and weak acid solutions leads to karst landscapes.   Flowing rivers, can be found in areas away from karst topography.