To find out how much Luke's baby sister weighs now, you need to add her birth weight to the weight she has gained.
Her birth weight: 714 pounds
Weight gained: 238 pounds
Now, add the two weights together:
\[ 714 + 238 = 952 \text{ pounds} \]
It looks like none of the options provided (10, 958, 912, or 9 pounds) match the correct calculation of 952 pounds. Please double-check the figures or options provided.