Taking examples from this loosely Googled page:
If you find, or calculate, the standard deviation (volatility) of the returns from your various investment classes you will find they range from low-risk (low volatility), such as Cash, to high-risk (high volatility), such as Strategic Growth.
The risk rating (volatility) is a good indicator of how reactive to market conditions your investment is likely to be. As you can see below, from mid-2010 to mid-2011 the High Risk index performed really well, but it was also most reactive when the market subsequently turned down.
The medium risk indices performed the best over the chart period, 2010 to 2013, but it could have turned out different. Generally, you choose your investment according to your "risk appetite" - how much you're willing to risk. You might play safe with, say, 30% cash, 60% medium risk, 10% high risk. (Then again, are you paying someone to manage cash, which you might be able to do for free in a bank?)
Assuming, for a moment, European (3.) and Intnl Equity Tracker (9.) had the same medium risk profile, then holding 50% & 50% would also add some currency diversification, which is usually advisable. However, the main choice is down to risk appetite.
To address your specific question: "my main interest for now is between Stockmarket Growth and Strategic Growth", first thing to do is check their volatilities.
For a further level of sophistication you can check how they are correlated against each other. If they are inversely correlated, i.e. one goes up when the other goes down, then holding some of each could be a good diversification. FYI: An Introduction to Investment Theory
The historical returns are important too, but the investment classes your pension fund is offering will probably be reasonably aligned on a risk-return basis. You should check though. I.e. do they line up on a plot of 3 year Return vs Volatility? e.g. the line through SA Cash - SA Bonds - Vol Target 20 - SA Equity.