Detailed Instructions: Given a prompt and two completions from a language model, select the completion that is the most fluent with respect to continuing the prompt. Fluency is defined by coherency and ease of understanding, not necessarily grammatical correctness. Generate either Completion A or Completion B.
Problem:Prompt: Thanks for small flat rate priority boxes. I'll remember to use 
Completion A: this. 
Completion B: them. (Thanks to David for this.)So, how do we get this thing up to speed on time?Well, i
Solution:
Completion B