Both of these verbs express the idea of knowing, but they are used in different contexts and are not interchangeable.
<em>Saber</em> is used when referring to facts or learned skills.
<em>¿Tú sabes manejar?</em> - You know how to drive?
<em>Ellos saben qué hora es</em>. - They know what time it is.
<em>Conocer</em> is used to convey familiarity.
<em>Ella los conoce.</em> - She knows them.
The context of the sentence is of familiarity - "Do you know California?" or "Are you familiar with California?" so the correct answer is b. <em>conoces</em>.
<h3>
Answer:</h3>
<em>¿Tú </em><em>conoces</em><em> California?</em>
