The synonym of ATTENUATE is:

Concept: Antonyms are those words that we can use to help repeated use of a single word in a judgement because they partake analogous meaning. 

• So, you need to find a word that shares analogous meaning to – attenuate.
• Complete answer Now, to answer the question let us look into the options that we've with us
• Option A: Repent means to feel or express sincere remorse or guilt about one's wrongdoing or sin.
• Option B: Make thin means to reduce commodities.
• Option C:  Force means to apply compulsion or coercion, especially with the use or trouble of violence.
• Option D:  Divide means to separate or be separated into corridors.

Hence option ‘B’ is the correct answer.