MKT,
yes, in c), i assume the following :
serving cell has CELL B defined as neighbour, with BCCH=12 and BSIC=01
The MS in the serving cell receives a SI5 containg the list of BCCH to measure. It includes ARFCN=12.
The MS measures the RxLev of frequency 12 and decodes the BSIC.
The MS reports the following to the BSC :
ARFCN=12, BSIC=01, RXLEV=-70dBm
The BSC will look at this report and guess that the reported cell is the CELL B.
But in fact, the MS has measured CELL Z, which is located 20km away, and is defined with BCCH=12 and BSIC=01 also.