Sentence improvement – dictionary skill verb: use the precise phrasal verb 'look up' with nouns; write 'look up a word in the dictionary' rather than 'look to a dictionary' for meaning.

Given sentence
'If you are not clear about the meaning of a word, it is wise to look to a dictionary.'

Concept/Approach
For checking meanings, the collocation is 'look up a word (in a dictionary)'. 'Look to' means 'depend on/seek help from' and is not used for finding definitions.

Step-by-step correction
Replace 'look to' → 'look up'.

Why other options are not ideal
'look for' → means 'seek' (not consult a reference).'look at' → means 'view'.'No improvement' → keeps the wrong prepositional verb.

Final Answer
look up