The correct answer is B) single-pass, fire-tube, scotch marine. The illustration MO-0064 depicts a single-pass, fire-tube, scotch marine boiler. This type of boiler is characterized by the combustion gases passing through the fire tubes once before exiting the boiler, which makes it a single-pass design. The fire-tube construction, where the hot gases pass through tubes surrounded by water, is typical of a scotch marine boiler. The other options are incorrect because forced circulation, coil-type boilers (A) have a different design, two-pass, scotch marine boilers (C) have the combustion gases passing through the fire tubes twice, and two-pass, water-tube boilers (D) have a fundamentally different configuration where the water flows through the tubes rather than the combustion gases.