The number of wires used depends on the bandwidth of the connection, not the type of cable. 10/100 use 4 wires (2 pair) and 1000 Mbps requires all 8 (4 pair). This is true for Cat5, 5e, 6, and 7.
I'm guessing you want to know which two pair 100 Mbps uses. A quick google search would have yielded your answer. In the future remember, Google is your friend
The answer is, 10/100 Mbps use 1, 2, 3 and 6.
Now that answer won't really be useful to you unless you know the A and B standards for cabling so this time, use google and go find that info.