A temporary benchmark has been established at the soffit of a chajja on a window opening, and its known elevation is 102.405 m above mean sea level. The backsight used to establish the height of the instrument is by an inverted staff reading of 1.80 m. A foresight reading with the same staff, held normally, is 1.215 m on a recently constructed plinth. The elevation of the plinth is

A temporary benchmark has been established at the soffit of a chajja o

1.	A temporary benchmark has been established at the soffit of a chajja on a window opening, and its known elevation is 102.405 m above mean sea level. The backsight used to establish the height of the instrument is by an inverted staff reading of 1.80 m. A foresight reading with the same staff, held normally, is 1.215 m on a recently constructed plinth. The elevation of the plinth is
A.	95.42 m O.D
B.	99.39 m O.D
C.	102.42 m O.D
D.	105.99 m O.D
Answer» C. 102.42 m O.D