I think
sqrt 7x^2 - 7*sqrt 49x
x sqrt7 - 7 (7) sqrtx
x sqrt7 - 49 sqrtx
2.16 is greater. To do this start from the left and compare the numbers. For example, 2 is the same in both but 1 is greater than 0, so the answer is 2.16.
A and B are points on j.
C and D are points on k.
Join AD and BC.
ABCD is a quadrilateral.
Clearly, the quadrilateral ABCD is the only plane that contains the points A, B, C and D.
Hence, correct answer is option A. Exactly one.