Hi Donald,
Let’s do this one in binary so you can see how it works.
146 - 10010010
147 - 10010011
As you can see the first 7 bits are the same, only the 7th bit is different. When a bit is the same we use a 0, when it’s different we use a 1. Our wildcard will be:
00000001 which in decimal is .1 which matches with answer A. We can use the same logic for answer C:
148 - 10010100
149 - 10010101
The first 7 bits are the same, only the 8th bit is different.
I hope this helps!
Rene