A height is not a tube length

A sufficiently long uniform narrow tube gives a vertical capillary rise of 10 mm under fixed wetting conditions. It is tilted to 45° from vertical while communicating with the same large reservoir. Assume the meniscus remains inside the tube and the narrow-tube approximation is valid.

What length along the tube lies between its crossing of the reservoir level and the meniscus?

Organize the givens & assumptions

Vertical rise = 10 mm
Tilt = 45° from vertical
Same surface tension, contact angle and radius

Static or initially equilibrated interfaces, constant uniform surface tension, negligible gravity-induced shape distortion where spherical or cylindrical curvature is specified, and negligible evaporation. Capillary heights use the narrow-tube model with equal gas pressures and a large reservoir.

A $10\sqrt2\ \mathrm{mm}$
B $10\ \mathrm{mm}$
C $5\sqrt2\ \mathrm{mm}$
D $20\ \mathrm{mm}$

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