"Who's that over there?" - "Oh, it's our new teacher, ____ just started work today"

51. “Who's that over there?" - "Oh, it's our new teacher, ____ just started work today."
​A. that​​​       B. who he​       ​C. which he​​       D. who
52. "Which CD did you get Marcus in the end?" – "I got him the one ____ said he really wanted to hear."
A. that​​​         B. who he​​        C. whose​​      D. which he
53. “Who did you send a Valentine's card to?" - "I'm not telling you, but it was someone ____ name begins with    “B”.” 
A. Which.      ​​B. who her ​​        C. whose​​     D. whose her
54. "Have you seen Jason Green's latest film?" – "Is that the one in ____ joins the FBI?”
A. which he ​​       B. that he​​       C. whom he ​     ​D. which 
55. "Why do you like Tania so much?” – “Well, she's one of the few people to ____ I can really talk." 
A. which ​​        B. whom​        ​C. that​​      ​D. who