Explanation:

The correct answer is option 'b', during.

Explanation:

In this sentence, we are referring to a specific time period, which is Christmas. When referring to a specific time period, we use the preposition 'during'.

Here's a breakdown of the options and why they are incorrect:

a) in: 'In' is used to refer to a general time frame or a season. For example, "I will be in Kolkata in December." However, in this sentence, we are referring to a specific time period (Christmas), so 'in' is not the correct choice.

Correct answer: during

b) during: This option is correct because it is used to refer to a specific time period. For example, "I will be in Kolkata during Christmas." It indicates that the person will be in Kolkata for the duration of Christmas.

c) at: 'At' is used to refer to a specific point in time. For example, "I will arrive at 8 PM." In this sentence, we are not referring to a specific point in time, but rather a time period (Christmas), so 'at' is not the correct choice.

d) along: 'Along' is used to indicate movement or accompanying someone or something. For example, "I will walk along the river." In this sentence, we are not talking about movement or accompanying someone or something, so 'along' is not the correct choice.

To summarize, the correct preposition to use in this sentence is 'during' because it refers to a specific time period (Christmas).