If $\text{BOY}$ is coded as $\text{ZPC}$, then $\text{GIRL}$ is coded as:

Let's evaluate the transformation logic from $\text{BOY}$ to $\text{ZPC}$:
1. Shift each letter forward by one alphabetical position ($+1$):
* $\text{B}\stackrel{+1}{\to }\text{C}$
* $\text{O}\stackrel{+1}{\to }\text{P}$
* $\text{Y}\stackrel{+1}{\to }\text{Z}$
This gives the intermediate string CPZ.

2. Reverse the entire order of the letters:
CPZ reversed becomes $\text{ZPC}$.

Now, apply this two-step pattern to the word $\text{GIRL}$:

1. Shift each letter forward by one position ($+1$):
* $\text{G}\stackrel{+1}{\to }\text{H}$
* $\text{I}\stackrel{+1}{\to }\text{J}$
* $\text{R}\stackrel{+1}{\to }\text{S}$
* $\text{L}\stackrel{+1}{\to }\text{M}$
This gives the intermediate string HJSM.

2. Reverse the entire sequence of letters:
HJSM reversed becomes $\text{MSJH}$.