Given that n+11nCn+n1nCn−1+...+21nC1+nC0=101023
⇒r=0∑nr+11nCr=101023(∴n+1Cr+1=r+1n+1nCr)
⇒r=0∑nn+11n+1Cr+1=101023
⇒n+11[n+1C1+n+1C2+...+n+1Cn+1]=101023
We know that C0n+C1n+C2n+.......+Cnn=2n
⇒n+12n+1−1=101023=10210−1
⇒n+1=10
⇒n=9
Hence this is the correct option.