Even thinking was a luxury he couldn't afford; the slightest pause would only deepen suspicion.
Sheraya immediately answered, "Because I have no choice!"
First, put the response out there, try to buy some time, give yourself time to think.
"Because you have no choice? What do you mean by that?" Granny asked.
"That is..." Sheraya took a deep breath and answered gravely, "Because we are survivors with nowhere to turn, so we have no choice."
"You mean you were forced into this situation, so you had no choice but to pretend to believe us?" Granny stared at Sheraya and asked again.
"Yes, exactly." Sheraya nodded, "Under the constant threat of death, I had no options. And since my companions chose to trust you, I too had to go along with the flow."
Immediately after, Sheraya turned to look at Dick, hostility arising in his eyes.