Mark Twain was restless when he was young and moved a lot, first

Mark Twain was restless when he was young and moved a lot, first eastward as a journeyman printer, up and down the Mississippi as （ ）.
A、a steamboat pilot
B、a guard
C、a servant
D、a sailor
【正确答案】：A
【题目解析】：马克·吐温少时就为生计而奔波，先是到东部当印刷工，后在密西西比河上做领航员，然后又西去内华达的金矿和银矿。