The U.S. Department of Health and Human Services sought to reassure Texans and the rest of the nation on Wednesday that a robust selection of affordable health insurance plans will be still available next year on the federal exchange despite the recent defection of a series of major insurers. Kathryn Martin, acting assistant secretary for planning and evaluation at HHS, brushed aside the significance to consumers of the rapid exit of insurers from the exchange as well as mounting reports of large rate increase requests from carriers who remain.