Nearly 515 blocks of San Francisco, including almost all of Nob Hill, were destroyed by the 1906 earthquake and fires. Many of San Francisco's "painted ladies"—its gaudy, nineteenth century Victorian houses—were lost in the disaster. Today, some 14,000 surviving houses have been preserved, particularly in the Cow Hollow, Mission, Pacific Heights, and Alamo Square districts.
Distinguished by their design characteristics, three styles of San Franciscan Victorians can be found today. The Italianate, which flourished in the 1970's, is characterized by a flat roof, slim pillars flanking the front door, and bays with windows that slant inward. The ornamentation of these narrow row houses was patterned after features of the Roman Classical styles. The Stick style, which peaked in popularity during the 1880s, added ornate woodwork outlines to the doors and windows. Other additions included the French cap, gables, and three-sided bays. Designs changed dramatically when the Queen Anne style. became the rage in the 1890s. Turrets, towers, steep gabled roofs, and glass art windows distinguished Queen Anne houses from their predecessors.
In the period after the earthquake, the Victorians came to be regarded as impossibly oldfashioned, but beginning around 1960, owners began peeling off stucco, tearing off false fronts, reapplying custom woodwork, and commissioning multi-hued paint jobs. Before long, many of these houses had been restored to their former splendor.
Which of the following is NOT one of the author's purposes in writing the passage？

A. To talk about the restoration of Victorian houses in San Francisco in the 1960s.
B. To discuss housing problems in San Francisco today.
C. To briefly trace the history of Victorian houses in San Francisco.
D. To categorize the three types of Victorian houses found in San Francisco.