¡Hola!
La persona que manea es el conductor.
<em>the person who drives is the driver.</em>
<em />
<em>a- el peatón = the pedestrian</em>
<em>b- la manzana = the apple </em>
<em>c- el conductor = the driver</em>
<em>-</em>
<em>☺☺☺</em>
Answer: había bebido
Cuando llegué, Marcela ya se había bebido cuatro vasos de leche.
When I arrived, Marcela had already drunk four glasses of milk.
Explanation: the Spanish plusquamperfect expresses the idea that something occurred before another action in the past. The action to arrive, it happened after the drinking action was over. In English this tense is named past perfect.
B) they shake each other's hand
The verb in this sentence,"se dan", comes from "darse", which is a reciprocal verb (verbo recíproco) and these verbs always talk about something that the speakers are mutually doing, so the other options wouldn't be correct because: 1) They aren't referring to the 3rd person of plural, 2) They aren't doing a reciprocated action.
Hope this helped you :)