Tubes are fixed to the tube sheet (a thick circular metallic plate) by the method of tube rolling and brazing (non-removable) or ferrule connection (removable). Thickness of the tube, sheet is normally __________ the outside diameter of the tube but in no case it should be less than 22 mm $$\left( {{{\frac{7}{8}}^{''}}} \right).$$

A. Half

B. Three fourth

C. Equal to

D. 1.5 times

Answer: Option C