The correct answer is 'look forward' (option B). The phrase 'look forward to' is a fixed expression meaning to anticipate with pleasure. Note that when 'to' functions as a preposition in this expression, it must be followed by a gerund (-ing form), not an infinitive. 'Look ahead' means to consider the future, 'see forward' is not a standard English expression, and 'think ahead' means to plan in advance.