An explanation on how to find tap bits would help greatly

(1 point) Note: The notation from this problem is from Understanding Cryptography by Paar and Pelzl. We conduct a known-plaintext attack against an LFSR. Through trial and error we have determined that the number of states is m=4. The plaintext given by 01111111=x0x1x2x3x4x5x6x7 when encrypted by the LFSR produced the ciphertext 10001101=y0y1y2y3y3y5y6y7 What are the tap bits of the LFSR? Please enter your answer as unspaced binary digits (e.g. 0101 to represent p3=0,p2=1,p1=0,p0=1 )