instruction:
This task is about creating an unanswerable question based on a given passage. Construct a question that looks relevant to the given context but is unanswerable. Following are a few suggestions about how to create unanswerable questions:
(i) create questions which require satisfying a constraint that is not mentioned in the passage
(ii) create questions which require information beyond what is provided in the passage in order to answer
(iii) replace an existing entity, number, date mentioned in the passage with other entity, number, date and use it in the question
(iv) create a question which is answerable from the passage and then replace one or two words by their antonyms or insert/remove negation words to make it unanswerable.
question:
Passage: Double fertilization refers to a process in which two sperm cells fertilize cells in the ovary. This process begins when a pollen grain adheres to the stigma of the pistil (female reproductive structure), germinates, and grows a long pollen tube. While this pollen tube is growing, a haploid generative cell travels down the tube behind the tube nucleus. The generative cell divides by mitosis to produce two haploid (n) sperm cells. As the pollen tube grows, it makes its way from the stigma, down the style and into the ovary. Here the pollen tube reaches the micropyle of the ovule and digests its way into one of the synergids, releasing its contents (which include the sperm cells). The synergid that the cells were released into degenerates and one sperm makes its way to fertilize the egg cell, producing a diploid (2n) zygote. The second sperm cell fuses with both central cell nuclei, producing a triploid (3n) cell. As the zygote develops into an embryo, the triploid cell develops into the endosperm, which serves as the embryo's food supply. The ovary now will develop into fruit and the ovule will develop into seed.
answer:
When a pollen tube fertilizes cells in the ovary, what is it called?


question:
Passage: From 1997 to 2004, Dell enjoyed steady growth and it gained market share from competitors even during industry slumps. During the same period, rival PC vendors such as Compaq, Gateway, IBM, Packard Bell, and AST Research struggled and eventually left the market or were bought out. Dell surpassed Compaq to become the largest PC manufacturer in 1999. Operating costs made up only 10 percent of Dell's $35 billion in revenue in 2002, compared with 21 percent of revenue at Hewlett-Packard, 25 percent at Gateway, and 46 percent at Cisco. In 2002, when Compaq merged with Hewlett Packard (the fourth-place PC maker), the newly combined Hewlett Packard took the top spot but struggled and Dell soon regained its lead. Dell grew the fastest in the early 2000s.
answer:
What did Dell enjoy from 1996 to 2004?


question:
Passage: Clickjacking, also known as "UI redress attack or User Interface redress attack", is a malicious technique in which an attacker tricks a user into clicking on a button or link on another webpage while the user intended to click on the top level page. This is done using multiple transparent or opaque layers. The attacker is basically "hijacking" the clicks meant for the top level page and routing them to some other irrelevant page, most likely owned by someone else. A similar technique can be used to hijack keystrokes. Carefully drafting a combination of stylesheets, iframes, buttons and text boxes, a user can be led into believing that they are typing the password or other information on some authentic webpage while it is being channeled into an invisible frame controlled by the attacker.
answer:

What is intended to be hijacked through a page overlay?