Transparent

Opaque is the opposite of the word Transparent.
Option 1) Translucent - this is an incorrect answer because the meaning of translucent is 'allowing light but not detailed shapes to pass through; semi-transparent or semi-transparent or glassy', which is not an antonym of the word transparent.
Option 2) Vague - this is an incorrect answer because the meaning of vague is 'uncertain, indefinite, or ambiguous character or meaning or unclear or cloudy or hazy', which is not an antonym of the word transparent.
Option 3) Blind - is wrong since the meaning of blind is "sightless or unseeing or unsighted or visually handicapped," which is not an antonym of the term transparent.
Option 4) Opaque - is the correct answer because the meaning of opaque is 'not capable of allowing light to pass through or preventing light from passing through' and this is the antonym of the term transparent since they have different meanings or are opposing in meaning