Explanation:

The correct option to complete the collocation is option 'B' - ran.

Collocation:
A collocation is a combination of words that are often used together and have a specific meaning when used in combination. In this case, the collocation is "ran the entire length of the room."

Meaning of the Sentence:
The sentence is describing the placement or position of a white leather sofa in a room. The sofa is positioned in such a way that it covers or extends throughout the entire length of the room.

Explanation of Options:
Let's go through each option to understand why option 'B' is the correct answer.

a) went: This option doesn't fit the sentence contextually because "went" is used for movement and doesn't convey the idea of the sofa's placement or position.

b) ran: This option is the correct answer. "Ran" is used to describe the extended or continuous placement of the sofa along the entire length of the room. It suggests a linear arrangement or positioning.

c) fell: This option doesn't make sense in the given context. "Fell" implies a sudden downward movement or collapse, which doesn't fit the description of the sofa's placement.

d) was: This option doesn't convey the idea of the sofa's placement running the entire length of the room. "Was" is a simple past tense of the verb "to be" and doesn't provide information about the sofa's positioning.

Conclusion:
The correct option to complete the collocation is 'B' - ran. It accurately describes the placement of the white leather sofa, indicating that it extends or covers the entire length of the room.