How do we fix the high variance in the data set?

$($a$)$ Add more complexity by introducing polynomial features

$($b$)$ Decrease Regularization term

$($c$)$ Getting more training data

$($d$)$ Reduce input features

Group of answer choices

$($a$)$ and $($b$)$

$($a$)$ and $($c$)$

$($c$)$ and $($d$)$

$($b$)$ and $($d$)$