Answer:
A series of sincere, simple sentences
Step-by-step explanation:
When writing a letter expressing thanks for a gift, there is no need to be too formal or use overly complex sentences. The use of indirect and pretentious sentences is also advised against since it may raise doubt regarding the true intentions of the letter. Thus, the best course of action is to write in simple, sincere, straight to the point sentences to express your gratitude for the gift.
The answer is: A series of sincere, simple sentences