refref Image and solve all $2$ question

$2.$Let $P(A_i)=2^{-i}.$ Calculate the upper bound for $P(u_i=1^5{A}_i)$ using union bound $($rounded to $3$ decimal places$).$

$0\mathrm{.}937$

$0\mathrm{.}984$

$0\mathrm{.}969$

$1$

$3.$Which of the following is$/$are the shortcomings of TD Learning that Q$-$learning resolves?

TD learning cannot provide values for $($state$,$ action$)$ pairs, limiting the ability to extract an optimal policy directly

TD learning requires knowledge of the reward and transition functions, which is not always available

TD learning is computationally expensive and slow compared to Q$-$learning

TD learning often suffers from high variance in value estimation, leading to unstable learning

TD learning cannot handle environments with continuous state and action spaces effectively