Answer:
Reflexive verb is <em>Tropezarse</em><em>.</em>
Sentence is : <em>Yo me tropiezo en la calle.</em>
Explanation:
In the sentence “<em>Yo camino de prisa y </em><em>me tropiezo</em><em> en la calle, una señora me recoge y pregunta cómo estoy</em>” (I walk fast and stumble in the street, a lady picks me up and asks me how I am) we find only one reflexive verb (tropezarse). A reflexive verb indicates that someone or something is performing an action on or for itself. In the sentence, the subject (I) performs the action on itself (I stumble in the street), and the subject and object of the verb refer to the same entity (the person stumble by himself or by herself // the person stumbles on their own).
Other verb options (<em>caminar, recogerme</em> and <em>preguntar</em>) are not reflexive because <em>recogerme</em> and <em>preguntar</em> were actions made by the lady on the person who stumbled in the street. On the other hand, “I walk fast” <em>(yo camino de prisa)</em> is a direct action, it is not reflexive (subject and object do not refer to the same entity).
