What will be the value of ‘a + b’ in the following equation?
$$\left[4 \left(3 + \left\{9 \times 6 \div 3 + \left\{12 \div \left(1 \div 1 \times 3\right)\right\}\right\}\right)\right] = 5^a \times 2^b$$

$$\left[4\left(3+\left\{9\times6\div3+\left\{12\div\left(1\div1\times3\right)\right\}\right\}\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(3+\left\{9\times6\div3+\left\{12\div\left(1\times3\right)\right\}\right\}\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(3+\left\{9\times6\div3+\left\{12\div3\right\}\right\}\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(3+\left\{9\times6\div3+4\right\}\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(3+\left\{9\times2+4\right\}\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(3+\left\{18+4\right\}\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(3+22\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$\left[4\left(25\right)\right]=5^a\times2^b$$

$$\Rightarrow$$  $$100=5^a\times2^b$$

$$\Rightarrow$$  $$25\times4=5^a\times2^b$$

$$\Rightarrow$$  $$5^2\times2^2=5^a\times2^b$$

Comparing both sides,  a = 2 and b = 2

$$\therefore\ $$a + b = 2 + 2 = 4

Hence, the correct answer is Option D