Here, As the exponent and base both are different, we can't simply it by using any mathematical rule, so we have to convert them into decimal then comparing with options.
So, 5^3/4 + 2^11/12
= 3.34 - 1.88
= 1.46
Which is most precise to 2^7/12 = 1.49
In short, Your Answer would be: Option D
Hope this helps!