From the given information, we know that z is equal to 3. Then, by substituting this value into the remaining equations, we have
x+y+3=14
and
y+4=7
From the last equation, we get
y=7-3
y=4
Now, by substituting this result into the first equation, we have
x+4+3=14
which gives
x+7=14
Then, by subtracting 7 to both sides, we have
x=7
Therefore, the solution of our systems is; X=7, y=4 and z=3. By comparing with the given options, the answer is option A.