A
Only one
B
Only two
C
All the three
D
None
Correct answer: (b) Only two
Explanation
- A
Only one
Only one. More than one of these missions supports micro-gravity work.
- B
Only two
Only two. Axiom-4 and Gaganyaan are human-spaceflight / station-class missions that support micro-gravity research. SpaDeX is a docking technology demo, not keyed as a micro-gravity lab.
- C
All the three
All three. SpaDeX is the extra.
- D
None
None. Two are keyed.
Summary. Official Set A key is (b) only two. Axiom-4 is a commercial station mission; Gaganyaan is India’s human spaceflight programme — both are micro-gravity research platforms. SpaDeX is ISRO’s docking experiment, not counted here as a micro-gravity research mission. Two of three.