The correct answer is B. By taxi
Step-by-step explanation:
In grammar, in the case of means of transportation the preposition that precedes them or is placed before they vary according to the type of transport and context. In this way, the preposition "by" is used only after verbs such as go, travel, etc. with different means of transportation including car, bus, taxi; the preposition "on" is used with bus, plane and train and the preposition "in" is used with car or in some cases with taxi. This implies, in the case of "He went to the stadium" the correct way to complete this sentence is "by taxi" because although it can be correct to use "in taxi" in this case the "taxi" refers to the general transport and also it is used after the verb "go" which makes "by taxi" the correct option.