Final answer:
The underlined word a'cerrada' in Spanish means a) 'closed', indicating that the door is not open and access is not currently possible.
Step-by-step explanation:
The underlined word in the sentence “Esa puerta está cerrada” means 'closed' in English. Therefore, the correct answer is a) closed. In Spanish, 'cerrada' is the feminine form of the past participle of 'cerrar,' which means 'to close.' Consequently, when referring to a door, 'cerrada' suggests that the door is not open and access is not possible unless it is unlocked or opened.