Consider the following activities :1.Spreading finely ground basalt rock on farmlands extensively2.Increasing the alkalinity of oceans by adding lime3.Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated watersHow many of the above activities are often considered and discussed for carbon capture and sequestration?

1. A

   Only one

   Only one. All three are discussed carbon-removal routes.

2. B

   Only two

   Only two. Enhanced rock weathering, ocean alkalinity and subsurface carbonated storage are all on the list.

3. C

   All three

   All three. Basalt on fields, lime in oceans, and pumping carbonated water into old mines / formations.

4. D

   None

   None. Each is a named CDR / CCS idea.

Summary. Official key is (c) all three. Spreading crushed basalt (enhanced weathering), adding alkalinity to the ocean, and injecting dissolved CO₂ into subsurface voids are all discussed carbon capture and sequestration pathways.