Answer
(a) correct.
(d) correct.
The others are not correct.
Work Step by Step
(a) correct.
Since the vertical asymptote $ x=a $ is determined by $\lim _{x \rightarrow a} g(x)=\infty $.
(d) correct.
Since the horizontal asymptote $ y=L $ is determined by $\lim _{x \rightarrow \infty} f(x)=L $.