1+2 + 3 + … + 49 + 50 + 49 + 48 + … + 3 + 2 + 1 is equal to:

2500
Required Sum =
$latex 2\left ( \frac{x\left ( x+1 \right )}{2} \right )+50&s=1$
$latex =>\frac{2\times 49\times 50}{2}+50=2500&s=1$
Hence option [D] is the right answer.