将抛物线y=3x²的图象先向上平移3个单位，再向右平移4个单位所得的解析式为(     )

A：$y=3{\left(x-3\right)}^2+4$

B：$y=3{\left(x+4\right)}^2-3$

C：$y=3{\left(x-4\right)}^2+3$

D：$y=3{\left(x-4\right)}^2-3$