Suppose that Y $=$ C $+$ I $+$ G $+$ X Z$.$ Which of the following can be illustrated by a rightward shift of the AD curve?$($a$)$ Increased technological innovation and political stability$($b$)$ A boom in major economies such as China, which are South Africas major trading partners$($c$)$ Depreciation of the local currency against the worlds major currencies due to speculationSelect one:a$.$Only $($a$)$ is correct.b$.$Only $($c$)$ is correct.c$.$Only $($b$)$ and $($c$)$ are correct.d$.$All the statements are correct.e$.$Only $($a$)$ and $($b$)$ are correct