Under Inland Rule 18, a sailing vessel underway is required to keep out of the way of which of the following?

Why B is correct

33 CFR §83.18(b)(iii) states that a sailing vessel underway shall keep out of the way of a vessel engaged in fishing. A sailing vessel is not required to keep out of the way of a power-driven vessel under Rule 18; the obligation runs the other direction per §83.18(a)(iv). 'Constrained by her draft' is not an Inland Rules category, and seaplanes are addressed separately in §83.18(e).