$1.$ A CRC code uses $x^6+x^5+x^4+1$ as the generator polynomial. This

CRC code will not detect the following error pattern:

$($a$)100001$

$($b$)1000010011$

$($c$)1110001$

$($d$)0000100000$

$2.$ The syndrome calculated at the receiver is found to be equal to $1.$ In

this case:

$($a$)$ Only the first bit is in error

$($b$)$ the received frame is in error

$($c$)$

only one bit is in error $($d$)$ neither $a,b$ or $c$