How many 14-bit strings (that is, bit strings of length 14) are there which: a. Start with the sub-string 011? b. Have weight 7 (i.e., contain exactly 7 1's) and start with the sub-string 011? c. Either start with 011 or end with 01 (or both)? d. Have weight 7 and either start with 011 or end with 01 (or both)?