The correct option is D the lady
Some verbs take two objects, a direct object and an indirect object. For
example, in the sentence 'Shaima gave a pen', there is only one object
'pen'. In the sentence 'Shaima gave me a pen', (or 'Shaima gave a pen to
me) there are two objects, 'me' and 'pen', where 'pen' is the direct object
and 'me' is the indirect object. The indirect object is the recipient of the direct object.
In the sentence, "the lady" is the indirect recipient of the verb "sent", because the direct recipient is "some flowers" and the lady receives the flowers. Hence the incorrect words are underlined, D is the correct option and A is incorrect. "The young man" is the subject and "sent" is the verb, hence options B and C are incorrect.
Note: The direct object answers the question 'what?' and the indirect object answers the question 'to who/whom?'