The question requires identifying the approximate length of the dead-end corridor from the provided architectural drawing. The dimension line at the bottom of the drawing explicitly labels the length of the building section containing the dead-end corridor as 31 ft 6 in. (9.6 m). This dimension extends from the exterior face of the far-left wall to the exterior face of the wall on the far side of the intersecting corridor. While the strict definition in the NFPA 101 Handbook measures a dead-end corridor to the centerline of the intersecting corridor, the explicit dimension on the plan is the most direct and intended value to be used for this question.

A. 25 ft 10 in. (7.8 m): This value is an incorrect calculation and does not correspond to any primary dimension shown on the drawing.

C. 69 ft 8 in. (21.2 m): This value cannot be reasonably derived from the dimensions provided for the left portion of the building containing the dead-end.

D. 84 ft 6 in. (25.7 m): This is the overall length of the entire building section depicted, not the specific length of the dead-end corridor.

1. NFPA 101®, Life Safety Code® Handbook, 2021 Edition, Commentary on Section 7.5.1.6, Exhibit 7.51. This source illustrates the standard method for measuring a dead-end corridor from its terminus to the centerline of the intersecting corridor, which provides a choice of egress paths. The provided drawing's dimension (31 ft 6 in.) deviates from this by measuring to the far wall, but it is the only explicit dimension given for that section.

2. Ching, F. D. K. (2014). Architectural Graphics. John Wiley & Sons. Chapter 3, "Architectural Drawing Systems," pp. 98-101. This text explains the conventions of architectural drawings, including the principle that explicit, written dimensions on a plan take precedence for interpretation over scaled measurements or calculations based on other, potentially conflicting, dimensions.

3. SFPE Handbook of Fire Protection Engineering, 5th Edition (2016). Chapter 54, "Egress System Design," Section 54.4.3. This chapter discusses the components of the means of egress, including corridors, and the importance of correctly interpreting design documents (like the provided exhibit) to evaluate compliance with code requirements such as dead-end limits.