Answer: Appeal; Enlist
Explanation: Enlist is a synonym for recruit, meaning, engage (a person or their help or support), fitting your desired context. On the other hand, appeal means for a serious or urgent request, best fitting for call.
Most likely, Gregor will open the door or someone in his family is going to force the door open. This will reveal Gregor's new form and the reader will get to see how Gregor's family reacts to his sudden transformation. Most likely they will be shocked and afraid at first.
The art of the twentieth century is largely a reflection of political, social, economic changes, which took place very quickly. As such, art has rejected traditional prejudices and concepts, in an attempt to respond to a faster lifestyle and challenges of the twentieth century. There are many different artistic directions, first as the heirs of modernism from the end of the nineteenth century, but completely new and independent. Art was thus associated with all the changes, openly criticized, and absorbed all these changes by open eyes, and remained independent. New perspectives, concepts, massive artistic productions, minimalism, have been created, as a way of fast and efficient artistic action and a reflection of reality. There has been a space for a variety of perceptions, concepts and artistic opinions, pop art as the thesis that everyone has fifteen minutes of fame, enabled the inclusion of different sensibilities and views.