Physics - NLM Question with Solution | TestHub

${\vec{F}}_4$ is the weight of the balloon, the pull of the Earth on the balloon. Its Newton's third-law pair is the gravitational pull of the balloon on the Earth, so option D is correct.

${\vec{F}}_1$ (balloon on hand) pairs with the hand pushing on the balloon, not with ${\vec{F}}_2$. ${\vec{F}}_3$ and ${\vec{F}}_4$ act on the same body, so they are not an action-reaction pair.