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Kepler's Laws & Planetary Motion question from NEET 2018

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Kepler's Laws & Planetary Motion

The kinetic energies of a planet in an elliptical orbit about the Sun, at positions A, B and C are KA, KB and KC, respectively. AC is the major axis and SB is perpendicular to AC at the position of the Sun S as shown in the figure. Then

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Answer: (b)

Angular momentum is conserved: $mvr =$ constant, so speed (and KE) is larger when the planet is nearer the Sun.
From the figure, the Sun S is near A: $SA < SB < SC$ .
So $v_A > v_B > v_C$ , giving $K_A > K_B > K_C$ .
So the answer is (b) $K_A > K_B > K_C$ .

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