Final answer:
Mrs. Forster is a friend who invites Lydia to join her on a trip to Brighton, making Lydia happy.
Step-by-step explanation:
Based on the given text excerpts, Mrs. Forster is portrayed as a character who influences Lydia's happiness.
The answer to the question is option B) Mrs. Forster is a friend who invites Lydia to join her on a trip to Brighton.
In the text, it is mentioned that Mrs. Forster takes Lydia to Brighton, which implies that she invites Lydia to join her on a trip. This event likely brings joy and excitement to Lydia, as she gets the opportunity to travel and experience something new.
This answer aligns with the information provided in the text and accurately describes Mrs. Forster's role in making Lydia happy.