Final answer:
The question requires identification of the most informal part of Serena Lawrence's cover letter. Informality can often be spotted through the absence of polite salutations, conventional capitalization, and standard email format, such as a missing subject line.
Step-by-step explanation:
The question is asking to identify which excerpt from Serena Lawrence's cover letter is the most informal in style. When evaluating the formality of language in cover letters, it is essential to consider elements like salutations, tone, and adherence to standard writing conventions. Based on the information provided, the excerpt that displays the most informal style is potentially the one that lacks a subject line, has a missing capital letter at the beginning of a sentence and lacks a polite salutation or expression of appreciation. However, without the exact text of Serena Lawrence's cover letter, it is difficult to provide a definite answer as the question does not specify which parts of the cover letter are written by her.