This shouldn't be marked wrong. It is the nicer way to say and mean that, but upenda would be like or love.
What shouldn't be marked wrong? You've posted in the forum ... we can't see what you wrote.
Also, "upenda" doesn't mean anything. Did you mean ...
upendo, a noun meaning "(charitable) love" or ...
upende meaning "you should love" / "it should love" [it = class 3, 11 or 14] / "love it!" [it = class 3, 11 or 14]
For Wanaomba jibu sasa I'd say all of the following are correct (as well as contracted forms):
"They would like an answer now."
"They would like the answer now."
"They are asking for an answer now."
"They are asking for the answer now."
For "They would like an answer now" I'd say:
Wangependa jibu sasa
Wanaomba jibu sasa