The correct answer is option 4: 60%. This means that there was a 60% increase in investment in the Electrical sector from 2005-06 to 2009-10.

To calculate the percentage increase, we can use the formula: (final value - initial value) / initial value * 100.

Let`s assume that the initial investment in 2005-06 was $100. To calculate the final value after a 60% increase, we can multiply the initial value by 1 + (percentage increase / 100).

In this case, the final value would be $100 * (1 + 60 / 100) = $100 * 1.6 = $160.

So, the investment increased from $100 in 2005-06 to $160 in 2009-10, which is a 60% increase.

Therefore, the correct answer is option 4: 60%.