'Mission Indradhanush' launched by the Government of India pertains to

Answer

immunization of children and pregnant women

(a) Immunization of children and pregnant women: Correct. Mission Indradhanush was launched by the Government of India to expand full immunization coverage for children and pregnant women.
(b) Construction of smart cities across the country: Incorrect. This relates to the Smart Cities Mission, not Mission Indradhanush.
(c) India's own search for the Earth-like planets in outer space: Incorrect. This is unrelated to public health; no such programme is called Mission Indradhanush.
(d) New Educational Policy: Incorrect. Mission Indradhanush has no connection with education policy; it is a health/immunization initiative.