Which sentence uses a formal writing style?

some people really want to get up in space, so now there's a market for space tourism.
we can't all be astronauts, but lots of us dream about the idea of space travel.
there was an article that told about how seven people got to make space flights.
a company plans to make space flights available to those who can afford the ticket price.

A company plans to make space flights available to those who can afford the ticket price.

D. A company plans to make space flights available to those who can afford the ticket price. Is your answer.

It's not A. Some people really want to get up in space, so now there's a market for space tourism because "get up in space" is not formal.

It's not B. We can't all be astronauts, but lots of us dream about the idea of space travel because "We can't all be" is not that formal.

It's not C.There was an article that told about how seven people got to make space flights because "that told about how" is not that formal.