For TCP$,$ the ACK number in the following scenario is:

a$.10.$

b$.30.$

c$.40.$

d$.60.$

e$.$ None of the above.

What is the checksum of $0101100011000011$ and $1011101000110010?$

a$.0101001011110110$

b$.1110110100001001$

c$.1010110100001001$

d$.0001001011110110$

c$.0001001011110101$