AFAIC, understanding the statistical underpinnings of Black Scholes etc. and the Greeks (other than delta) isn't relevant for most retail option traders. It's like asking someone for the time and they tell you how to build a watch :->). In this case, all you need to grasp is that options near the money benefit the most percentage wise from price change.
Let's use Joe Taxpayer's option prices for stock XYZ. Suppose one second after his pricing, XYZ jumps $2.50 with no change in implied volatility. Take the option prices and shift them down one row. I priced the missing ones. Column 1 is the strike price. Column 2 is his original call premiums. Column 3 is the new option price after a $2.50 rise in XYZ. Column 4 is the call's gain in dollars. Column 5 is the call's gain in percent. I hope this uploads properly.
XYZ = $178
175.00 2.15 3.70 $1.55 72%
177.50 0.95 2.15 $1.20 126%
180.00 0.35 0.95 $0.60 171%
182.50 0.14 0.35 $0.21 150%
185.00 0.07 0.14 $0.07 100%
187.50 0.04 0.07 $0.03 75%
190.00 0.03 0.04 $0.01 33%
As you can see, the ITM options have the larger dollar gain and the near the money have the larger percent gain.
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Suppose XYZ jumps another $2.50 (total of $5). Again, the same holds true.
175.00 2.15 5.75 $3.60 167%
177.50 0.95 3.70 $2.75 289%
180.00 0.35 2.15 $1.80 514%
182.50 0.14 0.95 $0.81 579%
185.00 0.07 0.35 $0.28 400%
187.50 0.04 0.14 $0.10 250%
190.00 0.03 0.07 $0.04 133%
Options provide leverage because you control 100 shares with a small premium, compared to the cost of the underlying. And if you compare an equi-dollar investment, it offers multiples of that (compare the returns from buying one $175 call with buying six $180 calls).
And yes, near expiry options contribute to the leverage because they have less time premium to lose as time premium decreases and intrinsic value increases as share price increases.