Which of the following are causes of slum growth?(a) Rapid growth of urban population(b) Unemployment in rural areas(c) Mass migration of unskilled and semi-skilled workers from rural to urban areas(d) Shortage of cheap residential accommodation in urban area.

• A. (a), (b) and (d)
• B. (b), (c) and (d)
• C. (d), (a) and (c)
• D. All of the above