To analyze how the use of third-person omniscient narration demonstrates the author's attitude toward the subject of marriage in "Hide and Seek" by Fyodor Sologub, let's consider the options:
A) by comparing the expectations of Serafima and Sergey for each other: This option highlights the different perspectives and expectations that characters have regarding their relationship, which can reveal the author's attitudes towards the complexities and challenges of marriage.
B) by providing the context for how Serafima and Sergey first met: This option focuses on their initial meeting, which may not directly address the author's overall attitude toward marriage as it pertains to their expectations and feelings about each other.
C) by describing the physical characteristics of Serafima and Sergey: While physical descriptions can provide insight into the characters, they may not directly reflect the author's attitude toward marriage.
D) by explaining the personality traits of Serafima and Sergey: This option could explore how their personalities influence their relationship, shedding light on the author's view of marriage dynamics.
Considering these points, A) by comparing the expectations of Serafima and Sergey for each other seems to be the most relevant choice, as it directly addresses the complexity of their relationship and provides insight into the author's attitude toward marriage through the characters' differing expectations.