There are several grammatical issues to consider in this long sentence. Since the main verb of the sentence follows a long inserted clause, check that it is correct. "The images...have proven useful" is fine. In the middle clause, "is" and "has" are parallel, and they are singular, like the singular noun that they refer to. Finally, there is no modifier error, as "a geostationary weather satellite" properly refers to "GOES-11."

Choice (B)'s error is evident by focusing on the main verb: "The images...has proven useful...." (C) changes the meaning of the sentence; rather than "proven useful," the images "have proven themselves," which is very different. (D) is very awkward, as is built with a passive construction: "Operated by the U.S....is GOES-11," rather than "GOES-11 is operated by the U.S." Finally (E) has a modifier error. "The images" are not "operated by the U.S.," the satellite is. Choice (A) is correct.