$1.$ Select the reason$($s$)$ for using a deep neural network

a$.$ Some patterns are very complex and can't be deciphered precisely by alternative methods.

b$.$ Deep nets are great at recognizing patterns and using them as building blocks in deciphering inputs.

c$.$ We now have the technology $-$ GPU $-$ to accelerate the training process by several folds of magnitude.

d$.($d$)($a$)$ and $($b$)$