Idiomatic similes in English are memorised fixed phrases, and "as fresh as a daisy" is the standard one used to describe someone who feels energetic, alert, and well rested. The image comes from how a daisy flower opens crisp and bright each morning, which became a symbol of renewed energy and liveliness in a person.
The remaining choices do not match this established idiom. "A rose" is more commonly linked with beauty or romance in other phrases, not freshness of energy. "Milk" typically suggests whiteness or purity rather than liveliness. "Dew" evokes morning moisture but has no accepted idiomatic pairing with "fresh" describing a person's state.
Since only "a daisy" completes the recognised idiom for feeling lively and rested, the correct answer is option 1, a daisy.