Goodluckyman saidWhich is the best way to avoid plateauing and to obtain good results.
You're nowhere near plateauing, so don't worry about it. Just lift, eat, and sleep.
Example if am doing leg press;
A)3 reps of (140X10) and moving to 150 as you get comfortable OR
B)3 reps of (130X10,140X10 and 150X10) and increasing to 140X10,150X10 and 160X10 as you get comfortable?
Your thoughts on the two options. A friend of mine told me today that B is the best option while I have been doing A.
Both are fine.
Generally, do as many as you can. You want to reach failure: the point at which you can't do another rep. You want to reach failure in the 6-12 rep range. You can reach failure on all sets, or you can just reach failure on the last set. Both of these techniques can be beneficial to you.
You can do 140x10 140x10 140x10
140x10 150x10 160x10
160x10 150x10 140x10
On either one of these, you might not fail exactly on the 10th rep.
It's possible on the first example that you do fail on the 10th rep each set, if your rests are long enough, and assuming that the 140 weight is challenging enough.
On the 2nd example, you should only fail on the last set, in theory. An alternative that you can do would be something more like 140x12 150x10 160x8, in which case you'll fail on each set. If your rests are short, you may fail sooner on each subsequent set, which is fine too.
On the 3rd example, you'll probably fail on the 10th rep each time, and as you get tired with each set, you reduce the weight with each set.
All of these are fine. Especially at your stage where you're just starting out, you don't need to overthink it too much. Just vary it.