Answer:
The answer is "/da-da/".
Step-by-step explanation:
Many words are similar in sound, especially when we look at lip movement we cannot be sure what speaker is saying and we are confused to observe. As in the given scenario when Jessica looks ate Ashlees's lips, she thought she is saying /ga-ga/ but that sound is actually presented is the acoustic signal for /ba-ba/ but the sound Jessica is most likely to hear is /da-da/, which is a mid point of ba and ga.